diff --git a/src/calculator.py b/src/calculator.py
index 5eb03460..59db8c09 100644
--- a/src/calculator.py
+++ b/src/calculator.py
@@ -10,3 +10,52 @@
 #   Multiplication: 8
 #   Division: 2
 #
+import enum
+
+
+class OperationType(enum.Enum):
+    SUM = 1
+    DIFFERENCE = 2
+    MULTIPLICATION = 3
+    DIVISION = 4
+
+
+def sum(a: int | float, b: int | float) -> int | float:
+    return a + b
+
+
+def difference(a: int | float, b: int | float) -> int | float:
+    return a - b
+
+
+def multiplication(a: int | float, b: int | float) -> int | float:
+    return a * b
+
+
+def division(a: int | float, b: int | float) -> int | float:
+    if b != 0:
+        return a / b
+    raise ValueError("Error: Division by zero")
+
+
+def operation(a: int | float, b: int | float, op: OperationType) -> int | float:
+    if op == OperationType.SUM:
+        return sum(a, b)
+    if op == OperationType.DIFFERENCE:
+        return difference(a, b)
+    if op == OperationType.MULTIPLICATION:
+        return multiplication(a, b)
+    if op == OperationType.DIVISION:
+        return division(a, b)
+
+    raise ValueError("Invalid operation")
+
+
+if __name__ == "__main__":  # pragma: no cover
+    num1 = float(input("Insert first number: "))
+    num2 = float(input("Insert second number: "))
+
+    print(f"SUM: {operation(num1, num2, OperationType.SUM)}")
+    print(f"Difference: {operation(num1, num2, OperationType.DIFFERENCE)}")
+    print(f"Multiplication: {operation(num1, num2, OperationType.MULTIPLICATION)}")
+    print(f"Division: {operation(num1, num2, OperationType.DIVISION)}")
diff --git a/tests/test_calculator.py b/tests/test_calculator.py
new file mode 100644
index 00000000..7107e8c6
--- /dev/null
+++ b/tests/test_calculator.py
@@ -0,0 +1,13 @@
+from src.calculator import operation, OperationType
+
+
+def test_calculator_operations() -> None:
+    assert operation(4, 2, op=OperationType.SUM) == 6  # SUM
+    assert operation(4, 2, op=OperationType.DIFFERENCE) == 2  # DIFFERENCE
+    assert operation(4, 2, op=OperationType.MULTIPLICATION) == 8  # MULTIPLICATION
+    assert operation(4, 2, op=OperationType.DIVISION) == 2  # DIVISION
+    try:
+        operation(4, 0, op=OperationType.DIVISION)
+        assert False
+    except ValueError as _:
+        assert True