diff --git a/123 b/123
new file mode 100644
index 0000000..190a180
--- /dev/null
+++ b/123
@@ -0,0 +1 @@
+123
diff --git a/calculator.c b/calculator.c
index 176f397..c2dd71f 100644
--- a/calculator.c
+++ b/calculator.c
@@ -8,8 +8,9 @@ void sub(int a, int b)
 {
 	printf("a - b = %d\n", a - b);
 }
-void mul()
+void mul(int a, int b)
 {
+    printf("a * b = %d\n", a * b)
 }
 void div()
 {