Fix return value of recursive factorial function

While the previous return functioned the same (because it was calling another factorial function), it was not recursive. All credit still to ThirtyThreeB, just thought this might confuse some people and was worth fixing!

calculator/calculator.js

@@ -33,7 +33,7 @@ function recursiveFactorial(n) {
   if (n===0){
     return 1;
   }
-  return n * factorial (n-1);
+  return n * recursiveFactorial (n-1);
 }
 
 module.exports = {