text: const { NotImplementedError } = require('../extensions/index.js');
  
  /**
   * 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) {
    while(n.toString().length > 1){
      n = n.toString().split('').map(el => Number(el)).reduce((sum, el) => sum += el)
    }
    return n
  }
  
  module.exports = {
    getSumOfDigits
  };
  