diff --git a/manual-testing-sandbox/test.js b/manual-testing-sandbox/test.js
index d2920d6af41..44c55402e93 100644
--- a/manual-testing-sandbox/test.js
+++ b/manual-testing-sandbox/test.js
@@ -7,7 +7,9 @@ class Calculator {
     this.result += number;
     return this;
   }
+
   subtract(number) {
+    this.result -= number;
     return this;
   }