12_calculator: Use operator instead of method in the solution (#571)

Author: Eduardo06sp

12_calculator/solution/calculator-solution.js

@@ -15,7 +15,7 @@ const multiply = function (array) {
 };
 
 const power = function (a, b) {
-  return Math.pow(a, b);
+  return a ** b;
 };
 
 const factorial = function (n) {