diff --git a/src/main/java/core/basesyntax/Calculate.java b/src/main/java/core/basesyntax/Calculate.java
new file mode 100644
index 00000000..f6a46513
--- /dev/null
+++ b/src/main/java/core/basesyntax/Calculate.java
@@ -0,0 +1,5 @@
+package core.basesyntax;
+
+public interface Calculate {
+    double calculate(double a, double b, char c);
+}
diff --git a/src/main/java/core/basesyntax/Calculator.java b/src/main/java/core/basesyntax/Calculator.java
new file mode 100644
index 00000000..b7b80394
--- /dev/null
+++ b/src/main/java/core/basesyntax/Calculator.java
@@ -0,0 +1,25 @@
+package core.basesyntax;
+
+public class Calculator implements Calculate {
+
+    @Override
+    public double calculate(double firstParameter, double secondParameter, char operation) {
+        switch (operation) {
+            case '+':
+                return firstParameter + secondParameter;
+            case '-':
+                return firstParameter - secondParameter;
+            case '*':
+                return firstParameter * secondParameter;
+            case '^':
+                return Math.pow(firstParameter, secondParameter);
+            case '/':
+                if (secondParameter == 0) {
+                    throw new ArithmeticException("Division by zero is not allowed.");
+                }
+                return firstParameter / secondParameter;
+            default:
+                throw new IllegalArgumentException("Invalid operation");
+        }
+    }
+}
diff --git a/src/main/java/core/basesyntax/HelloWorld.java b/src/main/java/core/basesyntax/HelloWorld.java
deleted file mode 100644
index 97db782b..00000000
--- a/src/main/java/core/basesyntax/HelloWorld.java
+++ /dev/null
@@ -1,8 +0,0 @@
-package core.basesyntax;
-
-/**
- * Feel free to remove this class and create your own.
- */
-public class HelloWorld {
-
-}
diff --git a/src/test/java/core/basesyntax/CalculatorTest.java b/src/test/java/core/basesyntax/CalculatorTest.java
new file mode 100644
index 00000000..b3ebb007
--- /dev/null
+++ b/src/test/java/core/basesyntax/CalculatorTest.java
@@ -0,0 +1,146 @@
+package core.basesyntax;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.Test;
+
+class CalculatorTest {
+    private static final double DELTA = 0.0001;
+    private Calculate calculator = new Calculator();
+    private double expected;
+    private double actual;
+
+    @Test
+    void calculate_additionWithTwoPositiveOperands_Ok() {
+        expected = 100.0;
+        actual = calculator.calculate(90.0, 10.0, '+');
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_additionWithTwoNegativeOperands_Ok() {
+        expected = - 150.0;
+        actual = calculator.calculate(-100.0, -50.0, '+');
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_additionWithPositiveAndNegativeOperands_Ok() {
+        expected = - 150.0;
+        actual = calculator.calculate(-200.0, 50.0, '+');
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_additionWithFirstOperandIsZero_Ok() {
+        expected = 50.0;
+        actual = calculator.calculate(0.0, 50.0, '+');
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_additionWithSecondOperandIsZero_Ok() {
+        expected = 60.0;
+        actual = calculator.calculate(60.0, 0.0, '+');
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_additionWithMinAndMaxDoubleValues_Ok() {
+        expected = Double.MAX_VALUE + Double.MIN_VALUE;
+        actual = calculator.calculate(Double.MAX_VALUE, Double.MIN_VALUE, '+');
+        assertEquals(expected, actual, DELTA);
+    }
+
+    @Test
+    void calculate_subtractionWithMinAndMaxDoubleValues_Ok() {
+        expected = Double.MAX_VALUE - Double.MIN_VALUE;
+        actual = calculator.calculate(Double.MAX_VALUE, Double.MIN_VALUE, '-');
+        assertEquals(expected, actual, DELTA);
+    }
+
+    @Test
+    void calculate_multiplicationWithMinAndMaxDoubleValues_Ok() {
+        expected = Double.MAX_VALUE * Double.MIN_VALUE;
+        actual = calculator.calculate(Double.MAX_VALUE, Double.MIN_VALUE, '*');
+        assertEquals(expected, actual, DELTA);
+    }
+
+    @Test
+    void calculate_divisionWithMinAndMaxDoubleValues_Ok() {
+        expected = Double.MAX_VALUE / Double.MIN_VALUE;
+        actual = calculator.calculate(Double.MAX_VALUE, Double.MIN_VALUE, '/');
+        assertEquals(expected, actual, DELTA);
+    }
+
+    @Test
+    void calculate_divisionByZero_NotOk() {
+        assertThrows(ArithmeticException.class, () -> {
+            calculator.calculate(2.0, 0.0, '/');
+        });
+    }
+
+    @Test
+    void calculate_raisingPositiveValueToThePositivePower_Ok() {
+        expected = 64.0;
+        actual = calculator.calculate(8.0, 2.0, '^');
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_raisingNegativeValueToThePositivePower_Ok() {
+        expected = 64.0;
+        actual = calculator.calculate(-8.0, 2.0, '^');
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_raisingPositiveValueToTheNegativePower_Ok() {
+        expected = 0.015625;
+        actual = calculator.calculate(8.0, -2.0, '^');
+        assertEquals(expected, actual, DELTA);
+    }
+
+    @Test
+    void calculate_raisingNegativeValueToTheNegativePower_Ok() {
+        expected = 0.015625;
+        actual = calculator.calculate(-8.0, -2.0, '^');
+        assertEquals(expected, actual, DELTA);
+    }
+
+    @Test
+    void calculate_raisingPositiveValueToZeroPower_Ok() {
+        expected = 1.0;
+        actual = calculator.calculate(8.0, 0.0, '^');
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_raisingNegativeValueToZeroPower_Ok() {
+        expected = 1.0;
+        actual = calculator.calculate(-8.0, 0.0, '^');
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_raisingZeroToPower_Ok() {
+        expected = 0.0;
+        actual = calculator.calculate(0.0, 10.0, '^');
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_raisingZeroToNegativePower() {
+        expected = Double.POSITIVE_INFINITY;
+        actual = calculator.calculate(0, -2, '^');
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void illegalOperation_NotOk() {
+        assertThrows(IllegalArgumentException.class, () -> {
+            calculator.calculate(2.0, 3.0, '#');
+        });
+    }
+}
diff --git a/src/test/java/core/basesyntax/HelloWorldTest.java b/src/test/java/core/basesyntax/HelloWorldTest.java
deleted file mode 100644
index 9a90d822..00000000
--- a/src/test/java/core/basesyntax/HelloWorldTest.java
+++ /dev/null
@@ -1,8 +0,0 @@
-package core.basesyntax;
-
-/**
- * Feel free to remove this class and create your own.
- */
-public class HelloWorldTest {
-
-}