Why is the return keyword not giving me the desired result?

Question

There is this challenge that I'd love to overcome. I've been stuck for almost 2 weeks. Here is the code:

 function multiply(top,bottom){ var num = top; var multiple = 2; while (num <= bottom){ num *= multiple; console.log(num); } return num; } console.log(multiply(5, 100));// expected outcome is 80

I'd love to return the last result from the console.log which is 80 but each time I use the return keyword, it doesn't bring the desired result.

Answer 1

You have another variable which keeps track of the next multiple, so that we can check it before we assign it to num .

 function multiply(top,bottom) { var num = top; var multiple = 2; var next = num * multiple; while(next < bottom) { num = next; next = num * multiple; } return num; } console.log(multiply(5, 100));

Answer 2

What's happening here is that you are multiplying a number and doing so until it reaches the desire result. But since it's not adding 1 with each step it can exceed the result. What you need is have separate variable to store the previous value:

 function multiply(top,bottom){ var num = top; var multiple = 2; while (top < bottom) { num = top; //get prevous value top *= multiple; console.log(num); } return num; } console.log(multiply(5, 100));// expected outcome is 80

Or having 1 less step is to do the calculation inside the while condition:

 function multiply(top,bottom){ var num = top; var multiple = 2; while ((top *= multiple) < bottom) { num = top; //get prevous value console.log(num); } return num; } console.log(multiply(5, 100));// expected outcome is 80