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

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.