diff --git a/pom.xml b/pom.xml
index edd71909..adca8e20 100644
--- a/pom.xml
+++ b/pom.xml
@@ -15,7 +15,7 @@
         <maven.checkstyle.plugin.configLocation>
             https://raw.githubusercontent.com/mate-academy/style-guides/master/java/checkstyle.xml
         </maven.checkstyle.plugin.configLocation>
-        <junit-jupiter.version>5.7.0</junit-jupiter.version>
+        <junit-jupiter.version>5.7.2</junit-jupiter.version>
     </properties>
 
     <dependencies>
diff --git a/src/main/java/core/basesyntax/Calculator.java b/src/main/java/core/basesyntax/Calculator.java
new file mode 100644
index 00000000..ff438c2d
--- /dev/null
+++ b/src/main/java/core/basesyntax/Calculator.java
@@ -0,0 +1,5 @@
+package core.basesyntax;
+
+public interface Calculator {
+    double calculate(double firstNum, double secondNum, char mathOperation);
+}
diff --git a/src/main/java/core/basesyntax/CalculatorImplementation.java b/src/main/java/core/basesyntax/CalculatorImplementation.java
new file mode 100644
index 00000000..ecfd1c58
--- /dev/null
+++ b/src/main/java/core/basesyntax/CalculatorImplementation.java
@@ -0,0 +1,45 @@
+package core.basesyntax;
+
+public class CalculatorImplementation implements Calculator {
+
+    @Override
+    public double calculate(double firstNum, double secondNum, char mathOperation) {
+        switch (mathOperation) {
+            case '+':
+                return addition(firstNum, secondNum);
+            case '-':
+                return subtraction(firstNum, secondNum);
+            case '/':
+                return division(firstNum, secondNum);
+            case '*':
+                return multiplication(firstNum, secondNum);
+            case '^':
+                return raiseToPower(firstNum, secondNum);
+            default:
+                throw new RuntimeException("Wrong input. Please try again");
+        }
+    }
+
+    private double addition(double firstNum, double secondNum) {
+        return firstNum + secondNum;
+    }
+
+    private double subtraction(double firstNum, double secondNum) {
+        return firstNum - secondNum;
+    }
+
+    private double division(double firstNum, double secondNum) {
+        if (secondNum == 0) {
+            throw new ArithmeticException("Divide by zero");
+        }
+        return firstNum / secondNum;
+    }
+
+    private double multiplication(double firstNum, double secondNum) {
+        return firstNum * secondNum;
+    }
+
+    private double raiseToPower(double firstNum, double secondNum) {
+        return Math.pow(firstNum, secondNum);
+    }
+}
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/CalculatorImplementationTest.java b/src/test/java/core/basesyntax/CalculatorImplementationTest.java
new file mode 100644
index 00000000..5ea25ba6
--- /dev/null
+++ b/src/test/java/core/basesyntax/CalculatorImplementationTest.java
@@ -0,0 +1,253 @@
+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 CalculatorImplementationTest {
+    private static final double DELTA = 0.00001;
+    private static final String DIVISION_OPERATION_MESSAGE = "Oops, operation of"
+            + " division doesn't work correctly";
+    private static final String MULTIPLICATION_OPERATION_MESSAGE = "Oops, operation of"
+            + " multiplication doesn't work correctly";
+    private static final String SUBTRACTION_OPERATION_MESSAGE = "Oops, operation of"
+            + " subtraction doesn't work correctly";
+    private static final String ADDITION_OPERATION_MESSAGE = "Oops, operation of"
+            + " addition doesn't work correctly";
+    private static CalculatorImplementation calculator;
+    private static double actual;
+    private static double expected;
+
+    @BeforeAll
+    static void beforeAll() {
+        calculator = new CalculatorImplementation();
+    }
+
+    @Test
+    void addition_TwoPositiveOperands_Ok() {
+        actual = calculator.calculate(200.3, 0.7, '+');
+        expected = 201.0;
+        assertEquals(actual, expected, DELTA, ADDITION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void addition_TwoNegativeOperands_Ok() {
+        actual = calculator.calculate(-20.65, -10.35, '+');
+        expected = -31.0;
+        assertEquals(actual, expected, DELTA, ADDITION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void addition_positiveAndNegativeOperands_Ok() {
+        actual = calculator.calculate(150.0, -90.5, '+');
+        expected = 59.5;
+        assertEquals(actual, expected, DELTA, ADDITION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void addition_NegativeAndPositiveOperands_Ok() {
+        actual = calculator.calculate(-30.45, 30.05, '+');
+        expected = -0.4;
+        assertEquals(actual, expected, DELTA, ADDITION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void addition_WithZero_Ok() {
+        actual = calculator.calculate(0.0, 222.22, '+');
+        expected = 222.22;
+        assertEquals(actual, expected);
+        actual = calculator.calculate(234.34, 0.0, '+');
+        expected = 234.34;
+        assertEquals(actual, expected, DELTA, ADDITION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void addition_MinAndMaxDoubleValues_Ok() {
+        actual = calculator.calculate(Double.MAX_VALUE, Double.MIN_VALUE, '+');
+        expected = Double.MAX_VALUE + Double.MIN_VALUE;
+        assertEquals(actual, expected, DELTA, ADDITION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void subtraction_TwoPositiveOperands_Ok() {
+        actual = calculator.calculate(125.75, 98.05, '-');
+        expected = 27.7;
+        assertEquals(actual, expected, DELTA, SUBTRACTION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void subtraction_TwoNegativeOperands_Ok() {
+        actual = calculator.calculate(-78.634, -18.995, '-');
+        expected = -59.639;
+        assertEquals(actual, expected, DELTA, SUBTRACTION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void subtraction_PositiveAndNegativeOperands_Ok() {
+        actual = calculator.calculate(123.456, -123.456, '-');
+        expected = 246.912;
+        assertEquals(actual, expected, DELTA, SUBTRACTION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void subtraction_NegativeAndPositiveOperands_Ok() {
+        actual = calculator.calculate(-232.98, 785.38, '-');
+        expected = -1018.36;
+        assertEquals(actual, expected, DELTA, SUBTRACTION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void subtraction_WithZero_Ok() {
+        actual = calculator.calculate(0.0, 444.44, '-');
+        expected = -444.44;
+        assertEquals(actual, expected, DELTA, SUBTRACTION_OPERATION_MESSAGE);
+        actual = calculator.calculate(555.58, 0.0, '-');
+        expected = 555.58;
+        assertEquals(actual, expected, DELTA, SUBTRACTION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void subtraction_MinAndMaxDoubleValues_Ok() {
+        actual = calculator.calculate(Double.MAX_VALUE, Double.MIN_VALUE, '-');
+        expected = Double.MAX_VALUE - Double.MIN_VALUE;
+        assertEquals(actual, expected, DELTA, SUBTRACTION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void multiplication_TwoPositiveOperands_Ok() {
+        actual = calculator.calculate(2.34, 2.210, '*');
+        expected = 5.1714;
+        assertEquals(actual, expected, DELTA, MULTIPLICATION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void multiplication_TwoNegativeOperands_Ok() {
+        actual = calculator.calculate(-5.65, -7.77, '*');
+        expected = 43.9005;
+        assertEquals(actual, expected, DELTA, MULTIPLICATION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void multiplication_PositiveAndNegativeOperands_Ok() {
+        actual = calculator.calculate(15.0, -3.5, '*');
+        expected = -52.5;
+        assertEquals(actual, expected, DELTA, MULTIPLICATION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void multiplication_NegativeAndPositiveOperands_Ok() {
+        actual = calculator.calculate(-10.45, 10.05, '*');
+        expected = -105.0225;
+        assertEquals(actual, expected, DELTA, MULTIPLICATION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void multiplication_WithZero_Ok() {
+        actual = calculator.calculate(0.0, 12.22, '*');
+        expected = 0;
+        assertEquals(actual, expected, DELTA, MULTIPLICATION_OPERATION_MESSAGE);
+        actual = calculator.calculate(15.15, 0.0, '*');
+        expected = 0;
+        assertEquals(actual, expected, DELTA, MULTIPLICATION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void multiplication_MinAndMaxDoubleValues_Ok() {
+        actual = calculator.calculate(Double.MAX_VALUE, Double.MIN_VALUE, '*');
+        expected = Double.MAX_VALUE * Double.MIN_VALUE;
+        assertEquals(actual, expected, DELTA, MULTIPLICATION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void division_TwoPositiveOperands_Ok() {
+        actual = calculator.calculate(60.30, 3.15, '/');
+        expected = 19.1428571;
+        assertEquals(actual, expected, DELTA, DIVISION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void division_TwoNegativeOperands_Ok() {
+        actual = calculator.calculate(-1.234, -0.456, '/');
+        expected = 2.70614035;
+        assertEquals(actual, expected, DELTA, DIVISION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void division_PositiveAndNegativeOperands_Ok() {
+        actual = calculator.calculate(15.0, -3.5, '/');
+        expected = -4.28571429;
+        assertEquals(actual, expected, DELTA, DIVISION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void division_NegativeAndPositiveOperands_Ok() {
+        actual = calculator.calculate(-10, 2, '/');
+        expected = -5;
+        assertEquals(actual, expected, DELTA, DIVISION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void division_WithZero_Ok() {
+        actual = calculator.calculate(0.0, 35.35, '/');
+        expected = 0;
+        assertEquals(actual, expected, DELTA, DIVISION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void division_WhenSecondOperandZero_NotOk() {
+        assertThrows(ArithmeticException.class, () -> calculator.calculate(100.55, 0, '/'));
+        assertThrows(ArithmeticException.class, () -> calculator.calculate(0, 0, '/'));
+    }
+
+    @Test
+    void division_MinAndMaxDoubleValues_Ok() {
+        actual = calculator.calculate(Double.MAX_VALUE, Double.MIN_VALUE, '/');
+        expected = Double.MAX_VALUE / Double.MIN_VALUE;
+        assertEquals(actual, expected, DELTA, DIVISION_OPERATION_MESSAGE);
+    }
+
+    @Test
+    void raising_ToAPowerTwoPositiveOperands_Ok() {
+        actual = calculator.calculate(2, 5, '^');
+        expected = 32;
+        assertEquals(actual, expected);
+    }
+
+    @Test
+    void raising_ToAPowerTwoNegativeOperands_Ok() {
+        actual = calculator.calculate(-2, -5, '^');
+        expected = -0.03125;
+        assertEquals(actual, expected);
+    }
+
+    @Test
+    void raising_ToAPowerPositiveAndNegativeOperands_Ok() {
+        actual = calculator.calculate(2, -5, '^');
+        expected = 0.03125;
+        assertEquals(actual, expected);
+    }
+
+    @Test
+    void raising_ToAPowerNegativeAndPositiveOperands_Ok() {
+        actual = calculator.calculate(-10, 2, '^');
+        expected = 100;
+        assertEquals(actual, expected);
+    }
+
+    @Test
+    void raising_ToAPowerWithZero_Ok() {
+        actual = calculator.calculate(0, 2, '^');
+        expected = 0;
+        assertEquals(actual, expected);
+        actual = calculator.calculate(2, 0, '^');
+        expected = 1;
+        assertEquals(actual, expected);
+    }
+
+    @Test
+    void illegalOperation_NotOk() {
+        assertThrows(RuntimeException.class, () -> calculator.calculate(20, 4, '#'));
+    }
+}
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 {
-
-}