diff --git a/src/main/java/core/basesyntax/Calculation.java b/src/main/java/core/basesyntax/Calculation.java
new file mode 100644
index 00000000..971836fb
--- /dev/null
+++ b/src/main/java/core/basesyntax/Calculation.java
@@ -0,0 +1,5 @@
+package core.basesyntax;
+
+public interface Calculation {
+    double calculate(double number1, double number2, char operation);
+}
diff --git a/src/main/java/core/basesyntax/Calculator.java b/src/main/java/core/basesyntax/Calculator.java
new file mode 100644
index 00000000..62d7b255
--- /dev/null
+++ b/src/main/java/core/basesyntax/Calculator.java
@@ -0,0 +1,21 @@
+package core.basesyntax;
+
+public class Calculator implements Calculation {
+    @Override
+    public double calculate(double number1, double number2, char operation) {
+        switch (operation) {
+            case '+':
+                return number1 + number2;
+            case '-':
+                return number1 - number2;
+            case '*':
+                return number1 * number2;
+            case '/':
+                return number1 / number2;
+            case '^':
+                return Math.pow(number1, number2);
+            default:
+                throw new IllegalOperationException("Illegal operator");
+        }
+    }
+}
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/main/java/core/basesyntax/IllegalOperationException.java b/src/main/java/core/basesyntax/IllegalOperationException.java
new file mode 100644
index 00000000..4689e504
--- /dev/null
+++ b/src/main/java/core/basesyntax/IllegalOperationException.java
@@ -0,0 +1,7 @@
+package core.basesyntax;
+
+public class IllegalOperationException extends RuntimeException {
+    public IllegalOperationException(String message) {
+        super(message);
+    }
+}
diff --git a/src/test/java/core/basesyntax/CalculatorTest.java b/src/test/java/core/basesyntax/CalculatorTest.java
new file mode 100644
index 00000000..f53bc560
--- /dev/null
+++ b/src/test/java/core/basesyntax/CalculatorTest.java
@@ -0,0 +1,212 @@
+package core.basesyntax;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+class CalculatorTest {
+    private static final double DELTA = 0.1;
+    private static Calculation count;
+
+    @BeforeAll
+    public static void beforeAll() {
+        count = new Calculator();
+    }
+
+    @Test
+    public void calculate_addition_positiveOperands() {
+        double actual = count.calculate(6, 7, '+');
+        assertEquals(13, actual);
+    }
+
+    @Test
+    public void calculate_addition_negativeOperands() {
+        double actual = count.calculate(-9, -11, '+');
+        assertEquals(-20, actual);
+    }
+
+    @Test
+    public void calculate_addition_positiveNegativeOperands() {
+        double actual = count.calculate(10, -20, '+');
+        assertEquals(-10, actual);
+    }
+
+    @Test
+    public void calculate_addition_zeroOperands() {
+        double actual = count.calculate(0, 0, '+');
+        assertEquals(0, actual);
+    }
+
+    @Test
+    public void calculate_addition_operandsMinValues() {
+        double actual = count.calculate(Double.MIN_VALUE, Double.MIN_VALUE, '+');
+        assertEquals(1.0E-323, actual);
+    }
+
+    @Test
+    public void calculate_addition_operandsMaxValues() {
+        double actual = count.calculate(Double.MAX_VALUE, Double.MAX_VALUE, '+');
+        assertTrue(Double.isInfinite(actual));
+    }
+
+    @Test
+    public void calculate_subtraction_positiveOperands() {
+        double actual = count.calculate(6, 7, '-');
+        assertEquals(-1, actual);
+    }
+
+    @Test
+    public void calculate_subtraction_negativeOperands() {
+        double actual = count.calculate(-9, -11, '-');
+        assertEquals(2, actual);
+    }
+
+    @Test
+    public void calculate_subtraction_positiveNegativeOperands() {
+        double actual = count.calculate(10, -20, '-');
+        assertEquals(30, actual);
+    }
+
+    @Test
+    public void calculate_subtraction_zeroOperands() {
+        double actual = count.calculate(0, 0, '-');
+        assertEquals(0, actual);
+    }
+
+    @Test
+    public void calculate_subtraction_operandsMinValues() {
+        double actual = count.calculate(Double.MIN_VALUE, Double.MIN_VALUE, '-');
+        assertEquals(0, actual);
+    }
+
+    @Test
+    public void calculate_subtraction_operandsMaxValues() {
+        double actual = count.calculate(Double.MAX_VALUE, Double.MAX_VALUE, '-');
+        assertEquals(0, actual);
+    }
+
+    @Test
+    public void calculate_multiplication_positiveOperands() {
+        double actual = count.calculate(6, 7, '*');
+        assertEquals(42, actual);
+    }
+
+    @Test
+    public void calculate_multiplication_negativeOperands() {
+        double actual = count.calculate(-9, -11, '*');
+        assertEquals(99, actual);
+    }
+
+    @Test
+    public void calculate_multiplication_positiveNegativeOperands() {
+        double actual = count.calculate(10, -20, '*');
+        assertEquals(-200, actual);
+    }
+
+    @Test
+    public void calculate_multiplication_zeroOperands() {
+        double actual = count.calculate(0, 2, '*');
+        assertEquals(0, actual);
+        actual = count.calculate(2, 0, '*');
+        assertEquals(0, actual);
+        actual = count.calculate(0, 0, '*');
+        assertEquals(0, actual);
+    }
+
+    @Test
+    public void calculate_multiplication_operandsMinValues() {
+        double actual = count.calculate(Double.MIN_VALUE, Double.MIN_VALUE, '*');
+        assertEquals(0, actual);
+    }
+
+    @Test
+    public void calculate_multiplication_operandsMaxValues() {
+        double actual = count.calculate(Double.MAX_VALUE, Double.MAX_VALUE, '*');
+        assertTrue(Double.isInfinite(actual));
+    }
+
+    @Test
+    public void calculate_division_positiveOperands() {
+        double actual = count.calculate(1.4, 1.2, '/');
+        assertEquals(1.2, actual, DELTA);
+    }
+
+    @Test
+    public void calculate_division_negativeOperands() {
+        double actual = count.calculate(-10, -2, '/');
+        assertEquals(5, actual);
+    }
+
+    @Test
+    public void calculate_division_positiveNegativeOperands() {
+        double actual = count.calculate(10, -2, '/');
+        assertEquals(-5, actual);
+    }
+
+    @Test
+    public void calculate_division_zeroDividendOperand() {
+        double actual = count.calculate(0, 5, '/');
+        assertEquals(0, actual);
+    }
+
+    @Test
+    public void calculate_division_zeroDividerOperand() {
+        double actual = count.calculate(5, 0, '/');
+        assertTrue(Double.isInfinite(actual));
+    }
+
+    @Test
+    public void calculate_division_operandsMinValues() {
+        double actual = count.calculate(Double.MIN_VALUE, Double.MIN_VALUE, '/');
+        assertEquals(1, actual);
+    }
+
+    @Test
+    public void calculate_division_operandsMaxValues() {
+        double actual = count.calculate(Double.MAX_VALUE, Double.MAX_VALUE, '/');
+        assertEquals(1, actual);
+    }
+
+    @Test
+    void calculate_raising_positiveNegativeValue_positivePower() {
+        double actual = count.calculate(2, 3, '^');
+        assertEquals(8, actual);
+        actual = count.calculate(-2, 3, '^');
+        assertEquals(-8, actual);
+    }
+
+    @Test
+    void calculate_raising_positiveNegativeValue_negativePower() {
+        double actual = count.calculate(2, -2, '^');
+        assertEquals(0.25, actual);
+        actual = count.calculate(-2, -2, '^');
+        assertEquals(0.25, actual);
+    }
+
+    @Test
+    void calculate_raising_positiveNegativeValue_zeroPower() {
+        double actual = count.calculate(2, 0, '^');
+        assertEquals(1, actual);
+        actual = count.calculate(-2, 0, '^');
+        assertEquals(1, actual);
+    }
+
+    @Test
+    void calculate_raising_zeroValue_positiveNegativePower() {
+        double actual = count.calculate(0, -2, '^');
+        assertTrue(Double.isInfinite(actual));
+        actual = count.calculate(0, 2, '^');
+        assertEquals(0, actual);
+    }
+
+    @Test
+    void calculate_illegalOperation_isNotOk() {
+        char invalidOperation = '%';
+        assertThrows(IllegalOperationException.class, () -> {
+            count.calculate(0, 2, invalidOperation);
+        });
+    }
+}
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 {
-
-}