Q.

Description:
Write a function, persistence, that takes in a positive parameter num and returns its multiplicative persistence, which is the number of times you must multiply the digits in num until you reach a single digit.

For example:

persistence(39) === 3 // because 39 = 27, 27 = 14, 1*4=4
// and 4 has only one digit

persistence(999) === 4 // because 999 = 729, 729 = 126,
// 126 = 12, and finally 1*2 = 2

persistence(4) === 0 // because 4 is already a one-digit number

A)

function persistence(num) {
   //code me
  let count = 0;
  let arr = [];
  while (num > 9) {
    arr = num.toString().split('');
    num = arr.reduce((a,b) => +a*+b)
    count++
  }
  return count++ 
}