diff --git a/calculator.py b/calculator.py
new file mode 100644
index 0000000..7c88e1c
--- /dev/null
+++ b/calculator.py
@@ -0,0 +1,20 @@
+#!/usr/bin/env python3
+"""Простой калькулятор"""
+
+
+def add(a, b):
+    return a + b
+
+
+def subtract(a, b):
+    return a - b
+
+
+def multiply(a, b):
+    return a * b
+
+
+def divide(a, b):
+    if b == 0:
+        raise ValueError("division by zero")
+    return a / b