text: /**
   * Given a number, replace this number with
   * the sum of its digits until we get to a one digit number.
   *
   * @param {Number} n
   * @return {Number}
   *
   * @example
   * For 100, the result should be 1 (1 + 0 + 0 = 1)
   * For 91, the result should be 1 (9 + 1 = 10, 1 + 0 = 1)
   *
   */
  function getSumOfDigits(n) {
    const arr = n.toString().split('').map((el) => Number(el));
    if (arr.length === 1) return arr[0];
    const num = arr.reduce((a, b) => a + b);
    return num > 9 ? getSumOfDigits(num) : num;
  }
  
  module.exports = getSumOfDigits;
  