[#96][프로그래머스][입문] 치킨 쿠폰

function solution(chicken) {
  let coupon = chicken;
  let service = 0;
  while (coupon >= 10) {
      service += Math.floor(coupon / 10); 
      coupon = Math.floor(coupon / 10) + coupon % 10; 
  }
  return service;
}