diff --git a/calculator.py b/calculator.py
index 0b521ee..792e4df 100644
--- a/calculator.py
+++ b/calculator.py
@@ -7,6 +7,9 @@ def multiply(a,b):
 
     def divide(a,b):
         return a/b
+    
+    def mod(a,b):
+        return a%b
 
     def minus(a,b):
         return a-b
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