Factorialize a Number (5)

JavaScript
1

Tell us what’s happening:
How does this code work?

Your code so far


function factorialize(num) {
  let n = 1;
  while(num >= 1){
    n = n * num;
    num--;
  }
  num = n;
  return num;
}

factorialize(5);

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Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-algorithm-scripting/factorialize-a-number

2

So if num is 5. Set a counter (n) to 1. Then loop num downwards from 5, setting the counter to its current value * num on each iteration. So


n == 1, num == 5
num >= 1, so
n = 1 * 5

n == 5, num == 4
num >= 1, so
n = 5 * 4

n == 20, num == 3
num >= 1, so
n = 20 * 3

n == 60, num == 2
num >= 1, so
n = 60 * 2

n == 120, num == 1
num >= 1, so
n = 120 * 1

n == 120, num == 0
num is not >= 1, so set num
num = 120
return num

The reason the counter n is set at 1 is that if 0 is passed, the while loop won’t start, and num will be set to 1, and returned (the factorial of 0 is 1)