Number Modification

//15 EXERCISE: FUNCTIONS/More Exercise/02. Number Modification.js
function numberModification(num) {
  'use strict'

  let str = String(num)

  const isAverageValueHigherThan5 = str => {

    let sum = 0
    let i

    for (i = 0; i < str.length; i++)
      sum += +str[i]

    let average = sum / i
    if (average > 5)
      return true
    else
      return false
  }

  while (!isAverageValueHigherThan5(str)) {
    str += '9'
  }

  console.log(str)
}