diff --git a/src/main/java/Calculations.java b/src/main/java/Calculations.java
new file mode 100644
index 0000000..a97d163
--- /dev/null
+++ b/src/main/java/Calculations.java
@@ -0,0 +1,37 @@
+public class Calculations {
+    public int calculateSquare(int num) {
+        return (num * num);
+    }
+
+    public int calculateFactorial(int num) {
+        if (num < 0) {
+            throw new IllegalArgumentException("Factorial is not defined for negative numbers");
+        }
+        if (num == 0 || num == 1) {
+            return 1; // Factorial of 0 and 1 is 1
+        }
+        int factorial = 1;
+        for (int i = 2; i <= num; i++) {
+            factorial *= i;
+        }
+        return factorial;
+    }
+
+    public static boolean isPrime(int num) {
+        if (num <= 1) {
+            return false; // Numbers less than or equal to 1 are not prime
+        }
+        if (num == 2 || num == 3) {
+            return true; // 2 and 3 are prime numbers
+        }
+        if (num % 2 == 0) {
+            return false; // Even numbers greater than 2 are not prime
+        }
+        for (int i = 3; i <= Math.sqrt(num); i += 2) {
+            if (num % i == 0) {
+                return false; // If num is divisible by any number from 3 to sqrt(num), it's not prime
+            }
+        }
+        return true; // If num is not divisible by any number from 2 to sqrt(num), it's prime
+    }
+}
diff --git a/src/test/java/CalculationsTest.java b/src/test/java/CalculationsTest.java
new file mode 100644
index 0000000..785d377
--- /dev/null
+++ b/src/test/java/CalculationsTest.java
@@ -0,0 +1,61 @@
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+public class CalculationsTest {
+
+    @Test
+    public void testCalculateSquare() {
+        Calculations calc = new Calculations();
+
+        // Test with a positive number
+        assertEquals(25, calc.calculateSquare(5));
+
+        // Test with a negative number
+        assertEquals(16, calc.calculateSquare(-4));
+
+        // Test with zero
+        assertEquals(0, calc.calculateSquare(0));
+
+        // Test with a large number
+        assertEquals(1000000, calc.calculateSquare(1000));
+    }
+
+    @Test
+    public void testCalculateFactorial() {
+        Calculations fact = new Calculations();
+
+        // Test with positive numbers
+        assertEquals(1, fact.calculateFactorial(0));
+        assertEquals(1, fact.calculateFactorial(1));
+        assertEquals(2, fact.calculateFactorial(2));
+        assertEquals(6, fact.calculateFactorial(3));
+        assertEquals(24, fact.calculateFactorial(4));
+        assertEquals(120, fact.calculateFactorial(5));
+
+        // Test with large number
+        assertEquals(3628800, fact.calculateFactorial(10));
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testNegativeNumber() {
+        Calculations fact = new Calculations();
+        fact.calculateFactorial(-5); // Should throw IllegalArgumentException
+    }
+
+    @Test
+    public void testIsPrime() {
+        // Prime
+        int[] primeNumbers = {2, 3, 5, 7, 11, 13};
+        int[] nonPrimeNumbers = {22, 33, 25, 4, 8, 14};
+
+        for(int i = 0; i < primeNumbers.length; i++) {
+            assertTrue(Calculations.isPrime(primeNumbers[i]));
+        }
+
+        for(int i = 0; i < nonPrimeNumbers.length; i++) {
+            assertFalse(Calculations.isPrime(nonPrimeNumbers[i]));
+        }
+    }
+}
+