diff --git a/src/main/c/Calculator/calculator.c b/src/main/c/Calculator/calculator.c
index bd6cdf3..f7900d9 100644
--- a/src/main/c/Calculator/calculator.c
+++ b/src/main/c/Calculator/calculator.c
@@ -72,6 +72,10 @@ double combination(int n, int r);
     }
     double performOperation(int choice, double num1, double num2) {
     switch (choice) {
+        case 1:
+            return num1 + num2;
+        case 2:
+            return num1 - num2;