From 97c634f97967477e297fa6d7f090608b7bf3678b Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Wed, 28 Feb 2024 09:43:13 -0500
Subject: [PATCH 01/20] finished Exercise27

---
 .../jonathanbirkey/chapter05/Exercise27.java  | 33 +++++++++++++++++++
 1 file changed, 33 insertions(+)
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise27.java

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise27.java b/src/com/github/jonathanbirkey/chapter05/Exercise27.java
new file mode 100644
index 0000000..c410e29
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise27.java
@@ -0,0 +1,33 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 27Dec2021
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise27 {
+  public static void main(String[] args) {
+    int yearsPerLine = 10;
+    int printedYears = 0;
+    int startYear = 101;
+    int endYear = 2100;
+    int totalLeapYears = 0;
+
+    for (int i = startYear; i <= endYear; i++) {
+      if ((i % 4 == 0 && i % 100 != 0) || (i % 400 == 0)) {
+        printedYears++;
+        if (printedYears == yearsPerLine) {
+          System.out.printf("%d\n", i);
+          printedYears = 0;
+        } else {
+          System.out.printf("%d ", i);
+        }
+        totalLeapYears++;
+      }
+    }
+    System.out.printf("\nNumber of leap years in this period: %d", totalLeapYears);
+  }
+}

From c4004f691e285ec99593dae2d57e31ab579f146a Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Wed, 28 Feb 2024 10:21:53 -0500
Subject: [PATCH 02/20] refactoring

---
 README.md                                               | 4 ++--
 src/com/github/jonathanbirkey/chapter05/Exercise19.java | 1 +
 src/com/github/jonathanbirkey/chapter05/Exercise27.java | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/README.md b/README.md
index 534d68d..36c49b6 100644
--- a/README.md
+++ b/README.md
@@ -8,8 +8,8 @@ This is the textbook I used to first learn programming in 2016. After having gra
 ## Notes
 | Tool | Name | Version | Link |
 |---|---|---|---|
-| IDE  | Eclipse | 2023-12 R | <https://www.eclipse.org/downloads/packages/installer> |
-| JVM  | Oracle Java JRE | 21.0.2 | Installed from Eclipse IDE installer |
+| IDE | Eclipse | 2023-12 R | <https://www.eclipse.org/downloads/packages/installer> |
+| Java | Oracle Java JRE | 21.0.2 | Installed from Eclipse IDE installer |
 | Code Formatter | google-java-format-eclipse-plugin | v1.20.0 | <https://github.com/google/google-java-format/releases/tag/v1.20.0> |
 
 ## google-java-format
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise19.java b/src/com/github/jonathanbirkey/chapter05/Exercise19.java
index f4518e4..3a2c542 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise19.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise19.java
@@ -29,3 +29,4 @@ public static void main(String[] args) {
     }
   }
 }
+
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise27.java b/src/com/github/jonathanbirkey/chapter05/Exercise27.java
index c410e29..7e29702 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise27.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise27.java
@@ -1,7 +1,7 @@
 /**
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
- * @created : 27Dec2021
+ * @created : 28Feb2024
  *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
  *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
  *     period.

From 7ec8ff4537c1b94dc8525a577ff11a9eb32846b0 Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Thu, 29 Feb 2024 06:39:13 -0500
Subject: [PATCH 03/20] finished exercise 28

---
 .../jonathanbirkey/chapter05/Exercise28.java  | 116 ++++++++++++++++++
 1 file changed, 116 insertions(+)
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise28.java

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise28.java b/src/com/github/jonathanbirkey/chapter05/Exercise28.java
new file mode 100644
index 0000000..e417170
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise28.java
@@ -0,0 +1,116 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display the first days of each month) Write a program that prompts the user to enter the
+ *     year and first day of the year, then displays the first day of each month in the year. For
+ *     example, if the user entered the year 2013, and 2 for Tuesday, January 1, 2013, your program
+ *     should display the following output:
+ *     <p>January 1, 2013 is Tuesday
+ *     <p>...
+ *     <p>December 1, 2013 is Sunday
+ */
+package com.github.jonathanbirkey.chapter05;
+
+import java.util.Scanner;
+
+public class Exercise28 {
+  public static void main(String[] args) {
+    Scanner input = new Scanner(System.in);
+    System.out.print("Enter year: (e.g., 2012): ");
+    int year = input.nextInt();
+    System.out.print("Enter first day of year (0 - Saturday, 1 - Sunday, 2 - Monday, etc): ");
+    int firstDay = input.nextInt();
+    input.close();
+
+    int futureDay = firstDay;
+    int daysInMonth = 0;
+    String monthStr;
+
+    for (int month = 1; month <= 12; month++) {
+      if (month == 1
+          || month == 3
+          || month == 5
+          || month == 7
+          || month == 8
+          || month == 10
+          || month == 12) {
+        daysInMonth = 31;
+      } else if (month == 4 || month == 6 || month == 9 || month == 11) {
+        daysInMonth = 30;
+      } else {
+        if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
+          daysInMonth = 29;
+        } else {
+          daysInMonth = 28;
+        }
+      }
+      switch (month) {
+        case 1:
+          monthStr = "January";
+          break;
+        case 2:
+          monthStr = "Febuary";
+          break;
+        case 3:
+          monthStr = "March";
+          break;
+        case 4:
+          monthStr = "April";
+          break;
+        case 5:
+          monthStr = "May";
+          break;
+        case 6:
+          monthStr = "June";
+          break;
+        case 7:
+          monthStr = "July";
+          break;
+        case 8:
+          monthStr = "August";
+          break;
+        case 9:
+          monthStr = "September";
+          break;
+        case 10:
+          monthStr = "October";
+          break;
+        case 11:
+          monthStr = "November";
+          break;
+        case 12:
+          monthStr = "December";
+          break;
+        default:
+          monthStr = "Invalid";
+      }
+      switch (futureDay) {
+        case 0:
+          System.out.printf("%s 1, %d is Saturday\n", monthStr, year);
+          break;
+        case 1:
+          System.out.printf("%s 1, %d is Sunday\n", monthStr, year);
+          break;
+        case 2:
+          System.out.printf("%s 1, %d is Monday\n", monthStr, year);
+          break;
+        case 3:
+          System.out.printf("%s 1, %d is Tuesday\n", monthStr, year);
+          break;
+        case 4:
+          System.out.printf("%s 1, %d is Wednesday\n", monthStr, year);
+          break;
+        case 5:
+          System.out.printf("%s 1, %d is Thursday\n", monthStr, year);
+          break;
+        case 6:
+          System.out.printf("%s 1, %d is Friday\n", monthStr, year);
+          break;
+        default:
+          System.out.println("Invalid");
+      }
+      futureDay = (futureDay + daysInMonth) % 7;
+    }
+  }
+}

From beaf0e8a0f1a89f14bb70faa1cb39ecc5c29a094 Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Thu, 29 Feb 2024 06:39:55 -0500
Subject: [PATCH 04/20] refactoring

---
 src/com/github/jonathanbirkey/chapter03/Exercise21.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/com/github/jonathanbirkey/chapter03/Exercise21.java b/src/com/github/jonathanbirkey/chapter03/Exercise21.java
index 7f8ebae..75567ba 100644
--- a/src/com/github/jonathanbirkey/chapter03/Exercise21.java
+++ b/src/com/github/jonathanbirkey/chapter03/Exercise21.java
@@ -32,7 +32,6 @@ public static void main(String[] args) {
     int year = input.nextInt();
     System.out.print("Enter month: 1-12: ");
     int m = input.nextInt();
-    input.close();
 
     if (m < 3) {
       m += 12;
@@ -42,6 +41,7 @@ public static void main(String[] args) {
     int k = year % 100;
     System.out.print("Enter the day of the month: 1-31: ");
     int q = input.nextInt();
+    input.close();
     int h = (q + ((26 * (m + 1)) / 10) + k + (k / 4) + (j / 4) + 5 * j) % 7;
     switch (h) {
       case 0:

From 3ce63be7617598e68bc8b9916c94f004a4f45e8e Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Mon, 4 Mar 2024 18:28:50 -0500
Subject: [PATCH 05/20] finished exercise 29

---
 .../jonathanbirkey/chapter05/Exercise29.java  | 140 ++++++++++++++++++
 1 file changed, 140 insertions(+)
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise29.java

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise29.java b/src/com/github/jonathanbirkey/chapter05/Exercise29.java
new file mode 100644
index 0000000..9f3e8e3
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise29.java
@@ -0,0 +1,140 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display calendars) Write a program that prompts the user to enter the year and first day
+ *     of the year and displays the calendar table for the year on the console. For example, if the
+ *     user entered the year 2013, and 2 for Tuesday, January 1, 2013, your program should display
+ *     the calendar for each month in the year, as follows:
+ *     <p>January 2013
+ *     <p>---------------------------
+ *     <p>Sun Mon Tue Wed Thu Fri Sat
+ *     <p>1 2 3 4 5
+ *     <p>6 7 8 9 10 11 12
+ *     <p>13 14 15 16 17 18 19
+ *     <p>20 21 22 23 24 25 26
+ *     <p>27 28 29 30 31
+ *     <p>
+ *     <p>...
+ *     <p>
+ *     <p>December 2013
+ *     <p>---------------------------
+ *     <p>Sun Mon Tue Wed Thu Fri Sat
+ *     <p>1 2 3 4 5 6 7
+ *     <p>8 9 10 11 12 13 14
+ *     <p>15 16 17 18 19 20 21
+ *     <p>22 23 24 25 26 27 28
+ *     <p>29 30 31
+ */
+package com.github.jonathanbirkey.chapter05;
+
+import java.util.Scanner;
+
+public class Exercise29 {
+  public static void main(String[] args) {
+    Scanner input = new Scanner(System.in);
+    System.out.print("Enter year: (e.g., 2012): ");
+    int year = input.nextInt();
+    System.out.print("Enter first day of year (0 - Saturday, 1 - Sunday, 2 - Monday, etc): ");
+    int firstDay = input.nextInt();
+    input.close();
+
+    int daysInMonth = 0;
+    String monthHeader;
+
+    for (int month = 1; month <= 12; month++) {
+      if (month == 1
+          || month == 3
+          || month == 5
+          || month == 7
+          || month == 8
+          || month == 10
+          || month == 12) {
+        daysInMonth = 31;
+      } else if (month == 4 || month == 6 || month == 9 || month == 11) {
+        daysInMonth = 30;
+      } else {
+        if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
+          daysInMonth = 29;
+        } else {
+          daysInMonth = 28;
+        }
+      }
+      switch (month) {
+        case 1:
+          monthHeader = "       January " + year;
+          break;
+        case 2:
+          monthHeader = "       Febuary " + year;
+          break;
+        case 3:
+          monthHeader = "        March " + year;
+          break;
+        case 4:
+          monthHeader = "        April " + year;
+          break;
+        case 5:
+          monthHeader = "         May " + year;
+          break;
+        case 6:
+          monthHeader = "         June " + year;
+          break;
+        case 7:
+          monthHeader = "         July " + year;
+          break;
+        case 8:
+          monthHeader = "        August " + year;
+          break;
+        case 9:
+          monthHeader = "      September " + year;
+          break;
+        case 10:
+          monthHeader = "       October " + year;
+          break;
+        case 11:
+          monthHeader = "       November " + year;
+          break;
+        case 12:
+          monthHeader = "       December " + year;
+          break;
+        default:
+          monthHeader = "Invalid";
+      }
+
+      System.out.printf(
+          "%s\n---------------------------\nSun Mon Tue Wed Thu Fri Sat\n", monthHeader);
+
+      int dayShift = 0;
+      if (firstDay > 0) {
+        dayShift = firstDay - 1;
+      } else {
+        dayShift = firstDay + 6;
+      }
+
+      for (int i = 0; i < dayShift; i++) {
+        System.out.print("    ");
+      }
+
+      for (int date = 1; date <= daysInMonth; date++) {
+        if (dayShift == 6) {
+          if (date < 10) {
+            System.out.printf("  %d\n", date);
+          } else {
+            System.out.printf(" %d\n", date);
+          }
+          dayShift = 0;
+        } else {
+          if (date < 10) {
+            System.out.printf("  %d ", date);
+          } else {
+            System.out.printf(" %d ", date);
+          }
+          dayShift++;
+        }
+      }
+      System.out.print("\n\n");
+
+      firstDay = (firstDay + daysInMonth) % 7;
+    }
+  }
+}

From e32c84a28e79852faf0baf7b205505a072680939 Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Thu, 7 Mar 2024 08:21:05 -0500
Subject: [PATCH 06/20] finished exercise 30

---
 .../jonathanbirkey/chapter05/Exercise30.java  | 41 +++++++++++++++++++
 .../jonathanbirkey/chapter05/Exercise31.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise32.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise33.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise34.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise35.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise36.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise37.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise38.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise39.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise40.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise41.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise42.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise43.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise44.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise45.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise46.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise47.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise48.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise49.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise50.java  | 15 +++++++
 .../jonathanbirkey/chapter05/Exercise51.java  | 15 +++++++
 22 files changed, 356 insertions(+)
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise30.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise31.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise32.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise33.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise34.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise35.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise36.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise37.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise38.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise39.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise40.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise41.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise42.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise43.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise44.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise45.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise46.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise47.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise48.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise49.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise50.java
 create mode 100644 src/com/github/jonathanbirkey/chapter05/Exercise51.java

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise30.java b/src/com/github/jonathanbirkey/chapter05/Exercise30.java
new file mode 100644
index 0000000..c4cf1fb
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise30.java
@@ -0,0 +1,41 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Financial application: compound value) Suppose you save $100 each month into a savings
+ *     account with the annual interest rate 5%. Thus, the monthly interest rate is 0.05 / 12 =
+ *     0.00417. After the first month, the value in the account becomes
+ *     <p>100 * (1 + 0.00417) = 100.417
+ *     <p>After the second month, the value in the account becomes
+ *     <p>(100 + 100.417) * (1 + 0.00417) = 201.252
+ *     <p>After the third month, the value in the account becomes
+ *     <p>(100 + 201.252) * (1 + 0.00417) = 302.507
+ *     <p>and so on.
+ *     <p>Write a program that prompts the user to enter an amount (e.g., 100), the annual interest
+ *     rate (e.g., 5), and the number of months (e.g., 6) then displays the amount in the savings
+ *     account after the given month.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+import java.util.Scanner;
+
+public class Exercise30 {
+  public static void main(String[] args) {
+    Scanner input = new Scanner(System.in);
+    System.out.print("Enter an amount (e.g., 100): ");
+    double monthlySavings = input.nextDouble();
+    System.out.print("Enter annual interest rate (e.g., 5): ");
+    double annualInterestRate = input.nextDouble();
+    double monthlyInterestRate = (annualInterestRate / 100) / 12;
+    System.out.print("Enter the number of months (e.g., 6): ");
+    int months = input.nextInt();
+    input.close();
+
+    double total = 0;
+
+    for (int i = 0; i < months; i++) {
+      total = (total + monthlySavings) * (1 + monthlyInterestRate);
+    }
+    System.out.printf("Amount in savings after %d months: %.3f", months, total);
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise31.java b/src/com/github/jonathanbirkey/chapter05/Exercise31.java
new file mode 100644
index 0000000..b2ecc18
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise31.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise31 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise32.java b/src/com/github/jonathanbirkey/chapter05/Exercise32.java
new file mode 100644
index 0000000..fa388ac
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise32.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise32 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise33.java b/src/com/github/jonathanbirkey/chapter05/Exercise33.java
new file mode 100644
index 0000000..9310c76
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise33.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise33 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise34.java b/src/com/github/jonathanbirkey/chapter05/Exercise34.java
new file mode 100644
index 0000000..5a28250
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise34.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise34 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise35.java b/src/com/github/jonathanbirkey/chapter05/Exercise35.java
new file mode 100644
index 0000000..c2c90a8
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise35.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise35 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise36.java b/src/com/github/jonathanbirkey/chapter05/Exercise36.java
new file mode 100644
index 0000000..6857864
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise36.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise36 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise37.java b/src/com/github/jonathanbirkey/chapter05/Exercise37.java
new file mode 100644
index 0000000..dab6746
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise37.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise37 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise38.java b/src/com/github/jonathanbirkey/chapter05/Exercise38.java
new file mode 100644
index 0000000..93ae612
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise38.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise38 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise39.java b/src/com/github/jonathanbirkey/chapter05/Exercise39.java
new file mode 100644
index 0000000..82fb0fe
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise39.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise39 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise40.java b/src/com/github/jonathanbirkey/chapter05/Exercise40.java
new file mode 100644
index 0000000..38cb720
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise40.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise40 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise41.java b/src/com/github/jonathanbirkey/chapter05/Exercise41.java
new file mode 100644
index 0000000..c1af0d2
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise41.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise41 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise42.java b/src/com/github/jonathanbirkey/chapter05/Exercise42.java
new file mode 100644
index 0000000..8a204cc
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise42.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise42 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise43.java b/src/com/github/jonathanbirkey/chapter05/Exercise43.java
new file mode 100644
index 0000000..832cee7
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise43.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise43 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise44.java b/src/com/github/jonathanbirkey/chapter05/Exercise44.java
new file mode 100644
index 0000000..cd934d9
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise44.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise44 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise45.java b/src/com/github/jonathanbirkey/chapter05/Exercise45.java
new file mode 100644
index 0000000..c95083c
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise45.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise45 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise46.java b/src/com/github/jonathanbirkey/chapter05/Exercise46.java
new file mode 100644
index 0000000..1c99188
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise46.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise46 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise47.java b/src/com/github/jonathanbirkey/chapter05/Exercise47.java
new file mode 100644
index 0000000..63b5bb8
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise47.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise47 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise48.java b/src/com/github/jonathanbirkey/chapter05/Exercise48.java
new file mode 100644
index 0000000..c9f9c0f
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise48.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise48 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise49.java b/src/com/github/jonathanbirkey/chapter05/Exercise49.java
new file mode 100644
index 0000000..b1fc424
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise49.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise49 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise50.java b/src/com/github/jonathanbirkey/chapter05/Exercise50.java
new file mode 100644
index 0000000..31be65c
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise50.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise50 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise51.java b/src/com/github/jonathanbirkey/chapter05/Exercise51.java
new file mode 100644
index 0000000..1cb46da
--- /dev/null
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise51.java
@@ -0,0 +1,15 @@
+/**
+ * @author : Jonathan Birkey
+ * @mailto : jonathan.birkey@gmail.com
+ * @created : 28Feb2024
+ *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
+ *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
+ *     period.
+ */
+package com.github.jonathanbirkey.chapter05;
+
+public class Exercise51 {
+  public static void main(String[] args) {
+    // TODO: solve
+  }
+}

From 1ea55ac364cb580d874a61d9e5b366538d467ae7 Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Thu, 7 Mar 2024 08:37:25 -0500
Subject: [PATCH 07/20] finished exercise 31

---
 .../jonathanbirkey/chapter05/Exercise31.java  | 41 +++++++++++++++++--
 1 file changed, 37 insertions(+), 4 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise31.java b/src/com/github/jonathanbirkey/chapter05/Exercise31.java
index b2ecc18..03a6265 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise31.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise31.java
@@ -2,14 +2,47 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Financial application: compute CD value) Suppose you put $10,000 into a CD with an annual
+ *     percentage yield of 5.75%. After one month, the CD is worth
+ *     <p>10000 + 10000 * 5.75 / 1200 = 10047.92
+ *     <p>After two months, the CD is worth
+ *     <p>10047.91 + 10047.91 * 5.75 / 1200 = 10096.06
+ *     <p>After three months, the CD is worth
+ *     <p>10096.06 + 10096.06 * 5.75 / 1200 = 10144.44
+ *     <p>and so on.
+ *     <p>Write a program that prompts the user to enter an amount (e.g., 10000), the annual
+ *     percentage yield (e.g., 5.75), and the number of months (e.g., 18) and displays a table as
+ *     presented in the sample run.
+ *     <p>Enter the initial deposit amount: 10000
+ *     <p>Enter annual percentage yield: 5.75
+ *     <p>Enter maturity period (number of months): 18
+ *     <p>Month CD Value
+ *     <p>1 100047.92
+ *     <p>2 10096.06
+ *     <p>...
+ *     <p>17 10846.57
+ *     <p>18 10898.54
  */
 package com.github.jonathanbirkey.chapter05;
 
+import java.util.Scanner;
+
 public class Exercise31 {
   public static void main(String[] args) {
-    // TODO: solve
+    Scanner input = new Scanner(System.in);
+    System.out.print("Enter the initial deposit amount: ");
+    double amount = input.nextDouble();
+    System.out.print("Enter annual percentage yield: ");
+    double APY = input.nextDouble();
+    System.out.print("Enter maturity period (number of months): ");
+    int months = input.nextInt();
+    input.close();
+
+    System.out.printf("Month\tCD Value\n");
+
+    for (int i = 1; i <= months; i++) {
+      amount = amount + (amount * (APY / 1200));
+      System.out.printf("%-7d %.2f\n", i, amount);
+    }
   }
 }

From c214fc315e8e95c75c9683fff19392c74e8eb9bf Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Thu, 7 Mar 2024 09:39:07 -0500
Subject: [PATCH 08/20] finished exercise 32

---
 .../jonathanbirkey/chapter05/Exercise32.java  | 38 +++++++++++++++++--
 1 file changed, 34 insertions(+), 4 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise32.java b/src/com/github/jonathanbirkey/chapter05/Exercise32.java
index fa388ac..bab3606 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise32.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise32.java
@@ -2,14 +2,44 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Game: lottery) Revise Listing 3.8, Lottery.java, to generate a lottery of a two-digit
+ *     number. The two digits in the number are distinct. (Hint: Generate the first digit. Use a
+ *     loop to continuously generate the second digit until it is different from the first digit.)
  */
 package com.github.jonathanbirkey.chapter05;
 
+import java.util.Scanner;
+
 public class Exercise32 {
   public static void main(String[] args) {
-    // TODO: solve
+    int lotteryDigit1 = (int) (Math.random() * 10);
+    int lotteryDigit2 = 0;
+    do {
+    	lotteryDigit2 = (int) (Math.random() * 10);
+    }while(lotteryDigit1 == lotteryDigit2);
+    
+    
+    Scanner input = new Scanner(System.in);
+    System.out.print("Enter your lotter pick (two digits): ");
+    int guess = input.nextInt();
+    input.close();
+
+    int guessDigit1 = guess / 10;
+    int guessDigit2 = guess % 10;
+
+    System.out.printf("The lottery number is %d%d\n", lotteryDigit1, lotteryDigit2);
+
+    if (guessDigit1 == lotteryDigit1 && guessDigit2 == lotteryDigit2) {
+      System.out.println("Exact match: you win $10,000");
+    } else if (guessDigit2 == lotteryDigit1 && guessDigit1 == lotteryDigit2) {
+      System.out.println("Match all digits: you win $3,000");
+    } else if (guessDigit1 == lotteryDigit1
+        || guessDigit1 == lotteryDigit2
+        || guessDigit2 == lotteryDigit1
+        || guessDigit2 == lotteryDigit2) {
+      System.out.println("Match one digit: you win $1,000");
+    } else {
+      System.out.println("Sorry, no match");
+    }
   }
 }

From c3cd77df1ec86d69d2c6c2d44590c4edd1e524b0 Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Thu, 7 Mar 2024 11:17:56 -0500
Subject: [PATCH 09/20] finished exercise 33

---
 .../jonathanbirkey/chapter05/Exercise33.java  | 20 +++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise33.java b/src/com/github/jonathanbirkey/chapter05/Exercise33.java
index 9310c76..000bb23 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise33.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise33.java
@@ -2,14 +2,26 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Perfect number) A positive integer is called a perfect number if it is equal to the sum
+ *     of all of its positive divisors, excluding itself. For example, 6 is the first perfect number
+ *     because 6 = 3 + 2 + 1. The next is 28 = 14 + 7 + 4 + 2 + 1. There are four perfect numbers <
+ *     10,000. Write a program to find all these four numbers.
  */
 package com.github.jonathanbirkey.chapter05;
 
 public class Exercise33 {
   public static void main(String[] args) {
-    // TODO: solve
+
+    for (int i = 1; i < 10000; i++) {
+      int sumPosDivisors = 0;
+      for (int j = 1; j <= (int) i / 2; j++) {
+        if (i % j == 0) {
+          sumPosDivisors += j;
+        }
+      }
+      if (i == sumPosDivisors) {
+        System.out.printf("Perfect number: %d\n", i);
+      }
+    }
   }
 }

From e67ea10c81aece8edcd4678ccdbda5f9900f67c7 Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Thu, 7 Mar 2024 11:27:14 -0500
Subject: [PATCH 10/20] finised exercise 34

---
 .../jonathanbirkey/chapter03/Exercise17.java  |  2 +
 .../jonathanbirkey/chapter05/Exercise34.java  | 67 +++++++++++++++++--
 2 files changed, 65 insertions(+), 4 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter03/Exercise17.java b/src/com/github/jonathanbirkey/chapter03/Exercise17.java
index dfc2af4..c63c1a3 100644
--- a/src/com/github/jonathanbirkey/chapter03/Exercise17.java
+++ b/src/com/github/jonathanbirkey/chapter03/Exercise17.java
@@ -31,6 +31,7 @@ public static void main(String[] args) {
         break;
       case 2:
         System.out.print("The computer is paper. ");
+        break;
       default:
         System.out.print("Invalide");
     }
@@ -43,6 +44,7 @@ public static void main(String[] args) {
         break;
       case 2:
         System.out.print("You are paper");
+        break;
       default:
         System.out.print("Invalide");
     }
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise34.java b/src/com/github/jonathanbirkey/chapter05/Exercise34.java
index 5a28250..c8aa969 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise34.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise34.java
@@ -2,14 +2,73 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Game: scissor, rock, paper) Programming Exercise 3.17 gives a program that plays the
+ *     scissor–rock–paper game. Revise the program to let the user continuously play until either
+ *     the user or the computer wins more than two times than its opponent.
  */
 package com.github.jonathanbirkey.chapter05;
 
+import java.util.Scanner;
+
 public class Exercise34 {
   public static void main(String[] args) {
-    // TODO: solve
+    Scanner input = new Scanner(System.in);
+    int computerWins = 0;
+    int userWins = 0;
+
+    while (computerWins < 2 && userWins < 2) {
+      int computerPick = (int) (Math.random() * 3);
+      System.out.print("scissor (0), rock (1), paper (2): ");
+      int userPick = input.nextInt();
+      switch (computerPick) {
+        case 0:
+          System.out.print("The computer is scissor. ");
+          break;
+        case 1:
+          System.out.print("The computer is rock. ");
+          break;
+        case 2:
+          System.out.print("The computer is paper. ");
+          break;
+        default:
+          System.out.print("Invalide");
+      }
+      switch (userPick) {
+        case 0:
+          System.out.print("You are scissor");
+          break;
+        case 1:
+          System.out.print("You are rock");
+          break;
+        case 2:
+          System.out.print("You are paper");
+          break;
+        default:
+          System.out.print("Invalide");
+      }
+      if (computerPick == userPick) {
+        System.out.println(" too. It is a draw");
+      } else if (computerPick == 0 && userPick == 1) {
+        System.out.println(". You won\n");
+        userWins++;
+      } else if (computerPick == 1 && userPick == 2) {
+        System.out.println(". You won\n");
+        userWins++;
+      } else if (computerPick == 2 && userPick == 0) {
+        System.out.println(". You won\n");
+        userWins++;
+      } else if (computerPick == 0 && userPick == 2) {
+        System.out.println(". You lost\n");
+        computerWins++;
+      } else if (computerPick == 1 && userPick == 0) {
+        System.out.println(". You lost\n");
+        computerWins++;
+      } else if (computerPick == 2 && userPick == 1) {
+        System.out.println(". You lost\n");
+        computerWins++;
+      }
+    }
+    input.close();
+    System.out.printf("\nFinal score\nComputer: %d\tUser: %d", computerWins, userWins);
   }
 }

From 5f2cabe20cca677219cb0de1be7ae6cb079e39ad Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Thu, 7 Mar 2024 11:35:52 -0500
Subject: [PATCH 11/20] finished exercise 35

---
 .../github/jonathanbirkey/chapter05/Exercise35.java   | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise35.java b/src/com/github/jonathanbirkey/chapter05/Exercise35.java
index c2c90a8..5e3a255 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise35.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise35.java
@@ -2,14 +2,17 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Summation) Write a program to compute the following summation:
+ *     <p>(1/1+sqrt(2)) + (1/sqrt(2)+sqrt(3)) + (1/sqrt(3)+sqrt(4)) + ... + (1/sqrt(624)+sqrt(625))
  */
 package com.github.jonathanbirkey.chapter05;
 
 public class Exercise35 {
   public static void main(String[] args) {
-    // TODO: solve
+    double summation = 0;
+    for (int i = 1; i <= 624; i++) {
+      summation += 1 / (Math.sqrt(i) + Math.sqrt(i + 1));
+    }
+    System.out.printf("Summation = %f", summation);
   }
 }

From 14340d21d71ba5f0f3af4f5b4d1b47607db405b8 Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Thu, 7 Mar 2024 14:57:50 -0500
Subject: [PATCH 12/20] finished exercise 36

---
 .../jonathanbirkey/chapter03/Exercise09.java  | 10 +++--
 .../jonathanbirkey/chapter05/Exercise36.java  | 41 +++++++++++++++++--
 2 files changed, 43 insertions(+), 8 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter03/Exercise09.java b/src/com/github/jonathanbirkey/chapter03/Exercise09.java
index c9b0f76..20a6a6d 100644
--- a/src/com/github/jonathanbirkey/chapter03/Exercise09.java
+++ b/src/com/github/jonathanbirkey/chapter03/Exercise09.java
@@ -10,8 +10,10 @@
  *     program that prompts the user to enter the first 9 digits and displays the 10-digit ISBN
  *     (including leading zeros). Your program should read the input as an integer. Here are sample
  *     runs:
- *     <p>Enter the first 9 digits of an ISBN as integer: 013601267 The ISBN-10 number is 0136012671
- *     Enter the first 9 digits of an ISBN as integer: 013031997 The ISBN-10 number is 013031997X
+ *     <p>Enter the first 9 digits of an ISBN as integer: 013601267
+ *     <p>The ISBN-10 number is 0136012671
+ *     <p>Enter the first 9 digits of an ISBN as integer: 013031997
+ *     <p>The ISBN-10 number is 013031997X
  */
 package com.github.jonathanbirkey.chapter03;
 
@@ -45,9 +47,9 @@ public static void main(String[] args) {
     int checksum =
         (d1 * 1 + d2 * 2 + d3 * 3 + d4 * 4 + d5 * 5 + d6 * 6 + d7 * 7 + d8 * 8 + d9 * 9) % 11;
     if (checksum == 10) {
-      System.out.printf("%d%d%d%d%d%d%d%d%dX\n", d1, d2, d3, d4, d5, d6, d7, d8, d9);
+      System.out.printf("The ISBN-10 number is %d%d%d%d%d%d%d%d%dX\n", d1, d2, d3, d4, d5, d6, d7, d8, d9);
     } else {
-      System.out.printf("%d%d%d%d%d%d%d%d%d%d\n", d1, d2, d3, d4, d5, d6, d7, d8, d9, checksum);
+      System.out.printf("The ISBN-10 number is %d%d%d%d%d%d%d%d%d%d\n", d1, d2, d3, d4, d5, d6, d7, d8, d9, checksum);
     }
   }
 }
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise36.java b/src/com/github/jonathanbirkey/chapter05/Exercise36.java
index 6857864..825a947 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise36.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise36.java
@@ -2,14 +2,47 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Business application: checking ISBN) Use loops to simplify Programming Exercise 3.9.
  */
 package com.github.jonathanbirkey.chapter05;
 
+import java.util.Scanner;
+
 public class Exercise36 {
   public static void main(String[] args) {
-    // TODO: solve
+    Scanner input = new Scanner(System.in);
+    System.out.print("Enter the first 9 digits of an ISBN as integer: ");
+    int number = input.nextInt();
+    input.close();
+    
+    int tempNumber = number;
+    int leadingZeroCounter = 0;
+    int checksum = 0;
+
+    for (int i = 9; i > 0; i--) {
+    	int digit = tempNumber % 10;
+    	tempNumber = tempNumber / 10;
+    	if(digit == 0) {
+    		leadingZeroCounter++;
+    	}else {
+    		leadingZeroCounter = 0;
+    	}
+    	checksum += digit * i;
+    }
+    
+    checksum = checksum % 11;
+    System.out.printf("The ISBN-10 number is ");
+    
+    if (checksum == 10) {
+    	for(int j = 0; j < leadingZeroCounter; j++) {
+    		System.out.print("0");
+    	}
+    	System.out.printf("%dX", number);
+    } else {
+    	for(int j = 0; j < leadingZeroCounter; j++) {
+    		System.out.print("0");
+    	}
+    	System.out.printf("%d%d", number, checksum);
+    }
   }
 }

From 06ab66c0b20059faff3316d418e8626ea3cf9c3c Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Sun, 10 Mar 2024 19:48:49 -0400
Subject: [PATCH 13/20] finished exercise 37, this one was interesting to solve
 using only loops

---
 .../jonathanbirkey/chapter05/Exercise37.java  | 35 ++++++++++++++++---
 1 file changed, 31 insertions(+), 4 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise37.java b/src/com/github/jonathanbirkey/chapter05/Exercise37.java
index dab6746..ab2dab9 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise37.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise37.java
@@ -2,14 +2,41 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Decimal to binary) Write a program that prompts the user to enter a decimal integer then
+ *     displays its corresponding binary value. Don’t use Java’s Integer.toBinaryString(int) in this
+ *     program.
  */
 package com.github.jonathanbirkey.chapter05;
 
+import java.util.Scanner;
+
 public class Exercise37 {
   public static void main(String[] args) {
-    // TODO: solve
+    Scanner input = new Scanner(System.in);
+    System.out.print("Enter a decimal integer: ");
+    int decimal = input.nextInt();
+    input.close();
+
+    int count = 0;
+    int binary = 0;
+
+    while (decimal > 0) {
+      if (decimal % 2 == 0) {
+        binary += 0;
+      } else {
+        binary += 1;
+      }
+      decimal = decimal / 2;
+      if (decimal > 0) {
+        binary = binary * 10;
+      }
+
+      count++;
+    }
+
+    for (int i = 0; i < count; i++) {
+      System.out.printf("%d", binary % 10);
+      binary = binary / 10;
+    }
   }
 }

From 3e1db122c032686425949f7a2a6ccdea888c066c Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Sun, 10 Mar 2024 19:59:52 -0400
Subject: [PATCH 14/20] finished exercise 38

---
 .../jonathanbirkey/chapter05/Exercise37.java  | 12 +++----
 .../jonathanbirkey/chapter05/Exercise38.java  | 33 ++++++++++++++++---
 2 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise37.java b/src/com/github/jonathanbirkey/chapter05/Exercise37.java
index ab2dab9..6f1950f 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise37.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise37.java
@@ -18,25 +18,25 @@ public static void main(String[] args) {
     input.close();
 
     int count = 0;
-    int binary = 0;
+    int binaryNum = 0;
 
     while (decimal > 0) {
       if (decimal % 2 == 0) {
-        binary += 0;
+        binaryNum += 0;
       } else {
-        binary += 1;
+        binaryNum += 1;
       }
       decimal = decimal / 2;
       if (decimal > 0) {
-        binary = binary * 10;
+        binaryNum = binaryNum * 10;
       }
 
       count++;
     }
 
     for (int i = 0; i < count; i++) {
-      System.out.printf("%d", binary % 10);
-      binary = binary / 10;
+      System.out.printf("%d", binaryNum % 10);
+      binaryNum = binaryNum / 10;
     }
   }
 }
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise38.java b/src/com/github/jonathanbirkey/chapter05/Exercise38.java
index 93ae612..030ed40 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise38.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise38.java
@@ -2,14 +2,39 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Decimal to octal) Write a program that prompts the user to enter a decimal integer and
+ *     displays its corresponding octal value. Don’t use Java’s Integer.toOctalString(int) in this
+ *     program.
  */
 package com.github.jonathanbirkey.chapter05;
 
+import java.util.Scanner;
+
 public class Exercise38 {
   public static void main(String[] args) {
-    // TODO: solve
+    Scanner input = new Scanner(System.in);
+    System.out.print("Enter a decimal integer: ");
+    int decimal = input.nextInt();
+    input.close();
+
+    int count = 0;
+    int octalNum = 0;
+
+    while (decimal > 0) {
+      octalNum += decimal % 8;
+      decimal = decimal / 8;
+      if (decimal > 0) {
+        octalNum = octalNum * 10;
+      }
+
+      count++;
+    }
+
+    // 127 = 177
+    // 127 ÷ 8 = 15(Quotient) and (7)Remainder
+    for (int i = 0; i < count; i++) {
+      System.out.printf("%d", octalNum % 10);
+      octalNum = octalNum / 10;
+    }
   }
 }

From 01d3d3e433ac58aa8e6518d86c76e43548a6ceff Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Sun, 10 Mar 2024 20:21:56 -0400
Subject: [PATCH 15/20] finished exercise 39

---
 .../jonathanbirkey/chapter05/Exercise39.java  | 34 ++++++++++++++++---
 1 file changed, 29 insertions(+), 5 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise39.java b/src/com/github/jonathanbirkey/chapter05/Exercise39.java
index 82fb0fe..406f58e 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise39.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise39.java
@@ -2,14 +2,38 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Financial application: find the sales amount) You have just started a sales job in a
+ *     department store. Your pay consists of a base salary and a commission. The base salary is
+ *     $5,000. The scheme shown below is used to determine the commission rate.
+ *     <p>Sales Amount - Commission Rate
+ *     <p>$0.01–$5,000 - 8%
+ *     <p>$5,000.01–$10,000 - 10%
+ *     <p>$10,000.01 and above - 12%
+ *     <p>Note this is a graduated rate. The rate for the first $5,000 is at 8%, the next $5,000 is
+ *     at 10%, and the rest is at 12%. If the sales amount is 25,000, the commission is 5,000 * 8 +
+ *     5,000 * 10 + 15,000 * 12 = 2,700
+ *     <p>Your goal is to earn $30,000 a year. Write a program that finds out the minimum number of
+ *     sales you have to generate in order to make $30,000.
  */
 package com.github.jonathanbirkey.chapter05;
 
 public class Exercise39 {
   public static void main(String[] args) {
-    // TODO: solve
+    double baseSalary = 5000;
+    double commission = 0;
+    double desiredEarnings = 30000;
+    double sales = 0;
+
+    while (commission + baseSalary < desiredEarnings) {
+      if (sales <= 5000) {
+        commission = sales * 0.08;
+      } else if (sales <= 10000) {
+        commission = (5000 * 0.08) + ((sales - 5000) * 0.10);
+      } else {
+        commission = (5000 * 0.08) + (5000 * .10) + ((sales - 10000) * 0.12);
+      }
+      sales++;
+    }
+    System.out.printf("You would need to make $%.2f in sales to make at least $30,0000.", sales);
   }
-}
+}
\ No newline at end of file

From c5756fd02a158bb484f7b243ca8f27d297c05081 Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Sun, 10 Mar 2024 20:33:43 -0400
Subject: [PATCH 16/20] finished exercise 40

---
 .../jonathanbirkey/chapter05/Exercise40.java  | 19 +++++++++++++++----
 1 file changed, 15 insertions(+), 4 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise40.java b/src/com/github/jonathanbirkey/chapter05/Exercise40.java
index 38cb720..0c10261 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise40.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise40.java
@@ -2,14 +2,25 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Simulation: heads or tails) Write a program that simulates flipping a coin one million
+ *     times and displays the number of heads and tails.
  */
 package com.github.jonathanbirkey.chapter05;
 
 public class Exercise40 {
   public static void main(String[] args) {
-    // TODO: solve
+    int coin = 0;
+    int heads = 0;
+    int tails = 0;
+    
+    for (int i = 0; i < 1000000; i++) {
+    	coin = (int)(Math.random()*2);
+    	if(coin == 1) {
+    		heads++;
+    	}else {
+    		tails++;
+    	}
+    }
+    System.out.printf("Heads: %d\nTails: %d",heads, tails);
   }
 }

From 12b996b282c9b7d685c6fae019ea855c1bdabd29 Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Mon, 11 Mar 2024 10:27:48 -0400
Subject: [PATCH 17/20] finished exercise 41

---
 .../jonathanbirkey/chapter05/Exercise41.java  | 35 ++++++++++++++++---
 1 file changed, 31 insertions(+), 4 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise41.java b/src/com/github/jonathanbirkey/chapter05/Exercise41.java
index c1af0d2..f32a71e 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise41.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise41.java
@@ -2,14 +2,41 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Occurrence of max numbers) Write a program that reads integers, finds the largest of
+ *     them, and counts its occurrences. Assume the input ends with number 0. Suppose you entered 3
+ *     5 2 5 5 5 0; the program finds that the largest is 5 and the occurrence count for 5 is 4. If
+ *     no input is entered, display "No numbers are entered except 0".
+ *     <p>(Hint: Maintain two variables, max and count. max stores the current max number and count
+ *     stores its occurrences. Initially, assign the first number to max and 1 to count. Compare
+ *     each subsequent number with max. If the number is greater than max, assign it to max and
+ *     reset count to 1. If the number is equal to max, increment count by 1.)
  */
 package com.github.jonathanbirkey.chapter05;
 
+import java.util.Scanner;
+
 public class Exercise41 {
   public static void main(String[] args) {
-    // TODO: solve
+    Scanner input = new Scanner(System.in);
+   
+    int max = 0;
+    int count = 0;
+    int number = -1;
+    
+    System.out.print("Enter Numbers: ");
+    
+    while(number != 0) {
+    	number = input.nextInt();
+    	if(number > max) {
+    		max = number;
+    		count = 1;
+    	} else if(number == max) {
+    		count++;
+    	}
+    	
+    }
+    input.close();
+    System.out.printf("The largest number is %d\n", max);
+    System.out.printf("The occurrence count of the largest number is %d", count);
   }
 }

From 54643ac0147c12082c6d13aa1a8ff17c2307c1d4 Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Mon, 11 Mar 2024 10:39:37 -0400
Subject: [PATCH 18/20] finished exercise 42

---
 .../jonathanbirkey/chapter05/Exercise42.java  | 28 ++++++++++++++++---
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise42.java b/src/com/github/jonathanbirkey/chapter05/Exercise42.java
index 8a204cc..8d933ee 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise42.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise42.java
@@ -2,14 +2,34 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Financial application: find the sales amount) Rewrite Programming Exercise 5.39 as
+ *     follows:
+ *     <p>Use a for loop instead of a do-while loop.
+ *     <p>Let the user enter COMMISSION_SOUGHT instead of fixing it as a constant.
  */
 package com.github.jonathanbirkey.chapter05;
 
+import java.util.Scanner;
+
 public class Exercise42 {
   public static void main(String[] args) {
-    // TODO: solve
+    Scanner input = new Scanner(System.in);
+    System.out.print("Enter commission sought: ");
+    double desiredCommission = input.nextDouble();
+    double commission = 0;
+    double sales = 0;
+
+    for (int i = 0; commission < desiredCommission; i++) {
+      if (sales <= 5000) {
+        commission = sales * 0.08;
+      } else if (sales <= 10000) {
+        commission = (5000 * 0.08) + ((sales - 5000) * 0.10);
+      } else {
+        commission = (5000 * 0.08) + (5000 * .10) + ((sales - 10000) * 0.12);
+      }
+      sales = i;
+    }
+
+    System.out.printf("You would need to make $%.2f in sales to make at least $%.2f in commision.", sales, desiredCommission);
   }
 }

From 1e24be700ba4e066ceb2378917bb4f554bb5c68b Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Wed, 13 Mar 2024 11:34:30 -0400
Subject: [PATCH 19/20] finished exercise 43

---
 .../jonathanbirkey/chapter05/Exercise43.java  | 23 +++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise43.java b/src/com/github/jonathanbirkey/chapter05/Exercise43.java
index 832cee7..6576f9b 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise43.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise43.java
@@ -2,14 +2,29 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Math: combinations) Write a program that displays all possible combinations for picking
+ *     two numbers from integers 1 to 7. Also display the total number of all combinations.
+ *     <p>1 2
+ *     <p>1 3
+ *     <p>...
+ *     <p>...
+ *     <p>The total number of all combinations is 21
  */
 package com.github.jonathanbirkey.chapter05;
 
 public class Exercise43 {
   public static void main(String[] args) {
-    // TODO: solve
+    int totalCombinations = 0;
+
+    for (int i = 1; i <= 7; i++) {
+      for (int j = 1; j <= 7; j++) {
+        if (j != i && j > i) {
+          System.out.printf("%d %d\n", i, j);
+          totalCombinations++;
+        }
+      }
+    }
+
+    System.out.printf("The total number of all combinations is %d", totalCombinations);
   }
 }

From be8453639b4d6be9e4c0060aa25b4949f0cd96dd Mon Sep 17 00:00:00 2001
From: Jonathan Birkey <Jonathan.Birkey@gmail.com>
Date: Wed, 13 Mar 2024 11:46:14 -0400
Subject: [PATCH 20/20] fixing format errors

---
 .../jonathanbirkey/chapter03/Exercise09.java  |  7 +++-
 .../jonathanbirkey/chapter05/Exercise32.java  |  7 ++--
 .../jonathanbirkey/chapter05/Exercise36.java  | 38 +++++++++----------
 .../jonathanbirkey/chapter05/Exercise40.java  | 16 ++++----
 .../jonathanbirkey/chapter05/Exercise41.java  | 23 ++++++-----
 .../jonathanbirkey/chapter05/Exercise44.java  | 19 ++++++++--
 6 files changed, 61 insertions(+), 49 deletions(-)

diff --git a/src/com/github/jonathanbirkey/chapter03/Exercise09.java b/src/com/github/jonathanbirkey/chapter03/Exercise09.java
index 20a6a6d..c0600aa 100644
--- a/src/com/github/jonathanbirkey/chapter03/Exercise09.java
+++ b/src/com/github/jonathanbirkey/chapter03/Exercise09.java
@@ -47,9 +47,12 @@ public static void main(String[] args) {
     int checksum =
         (d1 * 1 + d2 * 2 + d3 * 3 + d4 * 4 + d5 * 5 + d6 * 6 + d7 * 7 + d8 * 8 + d9 * 9) % 11;
     if (checksum == 10) {
-      System.out.printf("The ISBN-10 number is %d%d%d%d%d%d%d%d%dX\n", d1, d2, d3, d4, d5, d6, d7, d8, d9);
+      System.out.printf(
+          "The ISBN-10 number is %d%d%d%d%d%d%d%d%dX\n", d1, d2, d3, d4, d5, d6, d7, d8, d9);
     } else {
-      System.out.printf("The ISBN-10 number is %d%d%d%d%d%d%d%d%d%d\n", d1, d2, d3, d4, d5, d6, d7, d8, d9, checksum);
+      System.out.printf(
+          "The ISBN-10 number is %d%d%d%d%d%d%d%d%d%d\n",
+          d1, d2, d3, d4, d5, d6, d7, d8, d9, checksum);
     }
   }
 }
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise32.java b/src/com/github/jonathanbirkey/chapter05/Exercise32.java
index bab3606..f91e745 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise32.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise32.java
@@ -15,10 +15,9 @@ public static void main(String[] args) {
     int lotteryDigit1 = (int) (Math.random() * 10);
     int lotteryDigit2 = 0;
     do {
-    	lotteryDigit2 = (int) (Math.random() * 10);
-    }while(lotteryDigit1 == lotteryDigit2);
-    
-    
+      lotteryDigit2 = (int) (Math.random() * 10);
+    } while (lotteryDigit1 == lotteryDigit2);
+
     Scanner input = new Scanner(System.in);
     System.out.print("Enter your lotter pick (two digits): ");
     int guess = input.nextInt();
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise36.java b/src/com/github/jonathanbirkey/chapter05/Exercise36.java
index 825a947..dfe5aa9 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise36.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise36.java
@@ -14,35 +14,35 @@ public static void main(String[] args) {
     System.out.print("Enter the first 9 digits of an ISBN as integer: ");
     int number = input.nextInt();
     input.close();
-    
+
     int tempNumber = number;
     int leadingZeroCounter = 0;
     int checksum = 0;
 
     for (int i = 9; i > 0; i--) {
-    	int digit = tempNumber % 10;
-    	tempNumber = tempNumber / 10;
-    	if(digit == 0) {
-    		leadingZeroCounter++;
-    	}else {
-    		leadingZeroCounter = 0;
-    	}
-    	checksum += digit * i;
+      int digit = tempNumber % 10;
+      tempNumber = tempNumber / 10;
+      if (digit == 0) {
+        leadingZeroCounter++;
+      } else {
+        leadingZeroCounter = 0;
+      }
+      checksum += digit * i;
     }
-    
+
     checksum = checksum % 11;
     System.out.printf("The ISBN-10 number is ");
-    
+
     if (checksum == 10) {
-    	for(int j = 0; j < leadingZeroCounter; j++) {
-    		System.out.print("0");
-    	}
-    	System.out.printf("%dX", number);
+      for (int j = 0; j < leadingZeroCounter; j++) {
+        System.out.print("0");
+      }
+      System.out.printf("%dX", number);
     } else {
-    	for(int j = 0; j < leadingZeroCounter; j++) {
-    		System.out.print("0");
-    	}
-    	System.out.printf("%d%d", number, checksum);
+      for (int j = 0; j < leadingZeroCounter; j++) {
+        System.out.print("0");
+      }
+      System.out.printf("%d%d", number, checksum);
     }
   }
 }
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise40.java b/src/com/github/jonathanbirkey/chapter05/Exercise40.java
index 0c10261..d9fc920 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise40.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise40.java
@@ -12,15 +12,15 @@ public static void main(String[] args) {
     int coin = 0;
     int heads = 0;
     int tails = 0;
-    
+
     for (int i = 0; i < 1000000; i++) {
-    	coin = (int)(Math.random()*2);
-    	if(coin == 1) {
-    		heads++;
-    	}else {
-    		tails++;
-    	}
+      coin = (int) (Math.random() * 2);
+      if (coin == 1) {
+        heads++;
+      } else {
+        tails++;
+      }
     }
-    System.out.printf("Heads: %d\nTails: %d",heads, tails);
+    System.out.printf("Heads: %d\nTails: %d", heads, tails);
   }
 }
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise41.java b/src/com/github/jonathanbirkey/chapter05/Exercise41.java
index f32a71e..85818dd 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise41.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise41.java
@@ -18,22 +18,21 @@
 public class Exercise41 {
   public static void main(String[] args) {
     Scanner input = new Scanner(System.in);
-   
+
     int max = 0;
     int count = 0;
     int number = -1;
-    
+
     System.out.print("Enter Numbers: ");
-    
-    while(number != 0) {
-    	number = input.nextInt();
-    	if(number > max) {
-    		max = number;
-    		count = 1;
-    	} else if(number == max) {
-    		count++;
-    	}
-    	
+
+    while (number != 0) {
+      number = input.nextInt();
+      if (number > max) {
+        max = number;
+        count = 1;
+      } else if (number == max) {
+        count++;
+      }
     }
     input.close();
     System.out.printf("The largest number is %d\n", max);
diff --git a/src/com/github/jonathanbirkey/chapter05/Exercise44.java b/src/com/github/jonathanbirkey/chapter05/Exercise44.java
index cd934d9..644fae5 100644
--- a/src/com/github/jonathanbirkey/chapter05/Exercise44.java
+++ b/src/com/github/jonathanbirkey/chapter05/Exercise44.java
@@ -2,14 +2,25 @@
  * @author : Jonathan Birkey
  * @mailto : jonathan.birkey@gmail.com
  * @created : 28Feb2024
- *     <p>(Display leap years) Write a program that displays all the leap years, 10 per line, from
- *     101 to 2100, separated by exactly one space. Also display the number of leap years in this
- *     period.
+ *     <p>(Computer architecture: bit-level operations) A short value is stored in 16 bits. Write a
+ *     program that prompts the user to enter a short integer and displays the 16 bits for the
+ *     integer. Here are sample runs:
+ *     <p>Enter an integer: 5
+ *     <p>The bits are 0000000000000101
+ *     <p>
+ *     <p>Enter an integer: -5
+ *     <p>The bits are 1111111111111011
  */
 package com.github.jonathanbirkey.chapter05;
 
+import java.util.Scanner;
+
 public class Exercise44 {
   public static void main(String[] args) {
-    // TODO: solve
+    Scanner input = new Scanner(System.in);
+    System.out.print("Enter an integer: ");
+    short decimal = input.nextShort();
+    input.close();
+    System.out.printf("The bits are %d", decimal);
   }
 }