diff --git a/src/main/java/core/basesyntax/Calculator.java b/src/main/java/core/basesyntax/Calculator.java
new file mode 100644
index 00000000..cfa77b6c
--- /dev/null
+++ b/src/main/java/core/basesyntax/Calculator.java
@@ -0,0 +1,30 @@
+package core.basesyntax;
+
+public class Calculator implements CalculatorService {
+    @Override
+    public double calculate(double firstValue, double secondValue, char operationType) {
+        switch (operationType) {
+            case '+' : {
+                return firstValue + secondValue;
+            }
+            case '-' : {
+                return firstValue - secondValue;
+            }
+            case '*' : {
+                return firstValue * secondValue;
+            }
+            case '/' : {
+                if (firstValue != 0 && secondValue == 0) {
+                    throw new IllegalArgumentException("Can't divide by zero!");
+                }
+                return firstValue / secondValue;
+            }
+            case '^' : {
+                return Math.pow(firstValue, secondValue);
+            }
+            default: {
+                throw new IllegalArgumentException("Illegal operation type");
+            }
+        }
+    }
+}
diff --git a/src/main/java/core/basesyntax/CalculatorService.java b/src/main/java/core/basesyntax/CalculatorService.java
new file mode 100644
index 00000000..71c1925f
--- /dev/null
+++ b/src/main/java/core/basesyntax/CalculatorService.java
@@ -0,0 +1,5 @@
+package core.basesyntax;
+
+public interface CalculatorService {
+    double calculate(double valueA, double valueB, char operationType);
+}
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..5825819f
--- /dev/null
+++ b/src/test/java/core/basesyntax/CalculatorTest.java
@@ -0,0 +1,307 @@
+package core.basesyntax;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+
+class CalculatorTest {
+    private static final double DELTA = 0.00001;
+    private static CalculatorService calculatorService;
+    private double actual;
+    private double expected;
+
+    @BeforeAll
+    private static void beforeAll() {
+        calculatorService = new Calculator();
+    }
+
+    @Test
+    void calculate_addTwoPositiveNumbers_Ok() {
+        actual = calculatorService.calculate(10, 5, '+');
+        expected = 15;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_addTwoNegativeNumbers_Ok() {
+        actual = calculatorService.calculate(-5, -10, '+');
+        expected = -15;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_addPositiveAndNegativeNumbers_Ok() {
+        actual = calculatorService.calculate(-30, 50, '+');
+        expected = 20;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_additionWithZero_Ok() {
+        actual = calculatorService.calculate(0, 5, '+');
+        expected = 5;
+        assertEquals(expected, actual);
+        actual = calculatorService.calculate(0, 0, '+');
+        expected = 0;
+        assertEquals(expected, actual);
+        actual = calculatorService.calculate(50, 0, '+');
+        expected = 50;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_addTwoZeroNumbers_Ok() {
+        actual = calculatorService.calculate(0, 0, '+');
+        expected = 0;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_addTwoMaxNumbers_Ok() {
+        actual = calculatorService.calculate(Double.MAX_VALUE, Double.MAX_VALUE, '+');
+        expected = Double.POSITIVE_INFINITY;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_addTwoMinNumbers_Ok() {
+        actual = calculatorService.calculate(Double.MIN_VALUE, Double.MIN_VALUE, '+');
+        expected = 1.0E-323;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_subtractTwoPositiveNumbers_Ok() {
+        actual = calculatorService.calculate(200, 5, '-');
+        expected = 195;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_subtractTwoNegativeNumbers_Ok() {
+        actual = calculatorService.calculate(-50, -10, '-');
+        expected = -40;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_subtractPositiveAndNegativeNumbers_Ok() {
+        actual = calculatorService.calculate(-30, 50, '-');
+        expected = -80;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_subtractionWithZero_Ok() {
+        actual = calculatorService.calculate(0, 5, '-');
+        expected = -5;
+        assertEquals(expected, actual);
+        actual = calculatorService.calculate(50, 0, '-');
+        expected = 50;
+        assertEquals(expected, actual);
+        actual = calculatorService.calculate(0, 0, '-');
+        expected = 0;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_subtractTwoZeroNumbers_Ok() {
+        actual = calculatorService.calculate(0, 0, '-');
+        expected = 0;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_subtractTwoMaxNumbers_Ok() {
+        actual = calculatorService.calculate(Double.MAX_VALUE, Double.MAX_VALUE, '-');
+        expected = 0;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_subtractTwoMinNumbers_Ok() {
+        actual = calculatorService.calculate(Double.MIN_VALUE, Double.MIN_VALUE, '-');
+        expected = 0;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_multiplyTwoPositiveNumbers_Ok() {
+        actual = calculatorService.calculate(100, 100, '*');
+        expected = 10000;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_multiplyTwoNegativeNumbers_Ok() {
+        actual = calculatorService.calculate(-8, -20, '*');
+        expected = 160;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_multiplyPositiveAndNegativeNumbers_Ok() {
+        actual = calculatorService.calculate(-40, 40, '*');
+        expected = -1600;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_multiplicationWithZero_Ok() {
+        actual = calculatorService.calculate(0, 5, '*');
+        expected = 0;
+        assertEquals(expected, actual);
+        actual = calculatorService.calculate(50, 0, '*');
+        expected = 0;
+        assertEquals(expected, actual);
+        actual = calculatorService.calculate(0, 0, '*');
+        expected = 0;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_multiplyTwoZeroNumbers_Ok() {
+        actual = calculatorService.calculate(0, 0, '*');
+        expected = 0;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_multiplyTwoMaxNumbers_Ok() {
+        actual = calculatorService.calculate(Double.MAX_VALUE, Double.MAX_VALUE, '*');
+        expected = Double.POSITIVE_INFINITY;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_multiplyTwoMinNumbers_Ok() {
+        actual = calculatorService.calculate(Double.MIN_VALUE, Double.MIN_VALUE, '*');
+        expected = 0;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_divideTwoPositiveNumbers_Ok() {
+        actual = calculatorService.calculate(100, 10, '/');
+        expected = 10;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_divideTwoNegativeNumbers_Ok() {
+        actual = calculatorService.calculate(-8, -2, '/');
+        expected = 4;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_dividePositiveAndNegativeNumbers_Ok() {
+        actual = calculatorService.calculate(-160, 4, '/');
+        expected = -40;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_divideWithZero_Ok() {
+        actual = calculatorService.calculate(0, 5, '/');
+        expected = 0;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_divideWithZero_NotOk() {
+        assertThrows(IllegalArgumentException.class, () -> calculatorService.calculate(50, 0, '/'));
+    }
+
+    @Test
+    void calculate_divideWithTwoZeroValues_Ok() {
+        actual = calculatorService.calculate(0, 0, '/');
+        expected = Double.NaN;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_divideTwoMaxNumbers_Ok() {
+        actual = calculatorService.calculate(Double.MAX_VALUE, Double.MAX_VALUE, '/');
+        expected = 1;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_divideTwoMinNumbers_Ok() {
+        actual = calculatorService.calculate(Double.MIN_VALUE, Double.MIN_VALUE, '/');
+        expected = 1;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_raisePositiveNumberToPositivePower_Ok() {
+        actual = calculatorService.calculate(2, 5, '^');
+        expected = 32;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_raiseNegativeNumberToPositivePower_Ok() {
+        actual = calculatorService.calculate(-5, 2, '^');
+        expected = 25;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_raiseNegativeNumberToNegativePower_Ok() {
+        actual = calculatorService.calculate(-4, -2, '^');
+        expected = 0.0625;
+        assertEquals(expected, actual, DELTA);
+    }
+
+    @Test
+    void calculate_raisingToPowerWithZero_Ok() {
+        actual = calculatorService.calculate(0, 5, '^');
+        expected = 0;
+        assertEquals(expected, actual);
+        actual = calculatorService.calculate(50, 0, '^');
+        expected = 1;
+        assertEquals(expected, actual);
+        actual = calculatorService.calculate(0, 0, '^');
+        expected = 1;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_raisingNegativeToZeroPower_Ok() {
+        actual = calculatorService.calculate(-80, 0, '^');
+        expected = 1;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_raisingZeroToNegativePower_Ok() {
+        actual = calculatorService.calculate(0, -5, '^');
+        expected = Double.POSITIVE_INFINITY;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_raiseMaxNumberToMaxPower_Ok() {
+        actual = calculatorService.calculate(Double.MAX_VALUE, Double.MAX_VALUE, '^');
+        expected = Double.POSITIVE_INFINITY;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_raiseMinNumberToMinPower_Ok() {
+        actual = calculatorService.calculate(Double.MIN_VALUE, Double.MIN_VALUE, '^');
+        expected = 1;
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    void calculate_illegalOperationType_NotOk() {
+        assertThrows(IllegalArgumentException.class, () -> calculatorService.calculate(50, 0, '$'));
+        assertThrows(IllegalArgumentException.class, () -> calculatorService.calculate(50, 0, '4'));
+        assertThrows(IllegalArgumentException.class, () -> calculatorService.calculate(50, 0, 'h'));
+    }
+}
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 {
-
-}