diff --git a/calculator.c b/calculator.c
index 832dfd2..831478e 100644
--- a/calculator.c
+++ b/calculator.c
@@ -6,6 +6,7 @@ void add(int a, int b)
 }
 void sub()
 {
+    printf("a - b = %d\n", a - b)
 }
 void mul()
 {