code: private static function nbrConversionFormat($xVal, $places)
      {
          if ($places !== null) {
              if (is_numeric($places)) {
                  $places = (int) $places;
              } else {
                  return Functions::VALUE();
              }
              if ($places < 0) {
                  return Functions::NAN();
              }
              if (strlen($xVal) <= $places) {
                  return substr(str_pad($xVal, $places, '0', STR_PAD_LEFT), -10);
              }
  
              return Functions::NAN();
          }
  
          return substr($xVal, -10);
      }
docs: Formats a number base string value with leading zeroes.
  
  @param string $xVal The "number" to pad
  @param int $places The length that we want to pad this value
  
  @return string The padded "number"