code: function padNumbersToEqualLength(arr) {
    var maxLen = 0;
    var strings = arr.map(function(n) {
      var str = n.toString();
      maxLen = Math.max(maxLen, str.length);
      return str;
    });
    return strings.map(function(s) { return common.padLeft(s, maxLen); });
  }
docs: Given an array of numbers `arr`, return an array of the numbers as strings, right-justified and padded to the same length.