refactoring: case(for cbrt and factorial)

src/main/c/Calculator/calculator.c

@@ -93,7 +93,11 @@ double combination(int n, int r);
         case 10:
             return num1 * num1;
         case 11:
-            return num1 * num1 * num1;    
+            return num1 * num1 * num1;  
+        case 12:
+            return cbrt(num1);
+        case 13:
+            return factorial(num1);