Completing the fourth portion

Calculator.java

@@ -0,0 +1,23 @@
+public class Calculator {
+
+    public static double add(double a, double b) {
+        return a + b;
+    }
+
+    public static double subtract(double a, double b) {
+        return a - b;
+    }
+
+    public static double multiply(double a, double b) {
+        return a * b;
+    }
+    public static double divide(double a, double b) {
+    if (b == 0) {
+        // final agreed behavior
+        throw new ArithmeticException("Cannot divide by zero");
+    }
+    // keep rounding from master (or remove if you prefer)
+    return Math.round((a / b) * 100.0) / 100.0;
+    }
+
+}

HelloWorld.java

@@ -1,5 +1,15 @@
 public class HelloWorld {
-  public static void main(String[] args) {
-    System.out.println("Hello world!");
-  }
+    public static void main(String[] args) {
+        Student s = new Student("Alice", 20);
+        System.out.println("Student Name: " + s.getName());
+        System.out.println("Student Age: " + s.getAge());
+
+        System.out.println("2 + 3 = " + Calculator.add(2, 3));
+        System.out.println("7 - 4 = " + Calculator.subtract(7, 4));
+        System.out.println("6 * 5 = " + Calculator.multiply(6, 5));
+        System.out.println("8 / 2 = " + Calculator.divide(8, 2));
+
+
+
+    }
 }

Student.java

@@ -0,0 +1,30 @@
+public class Student {
+    private String name;
+    private int age;
+
+    // Constructor
+    public Student(String name, int age) {
+        this.name = name;
+        this.age = age;
+    }
+
+    // Getter for name
+    public String getName() {
+        return name;
+    }
+
+    // Setter for name
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    // Getter for age
+    public int getAge() {
+        return age;
+    }
+
+    // Setter for age
+    public void setAge(int age) {
+        this.age = age;
+    }
+}