code: public function precision($n)
      {
          if (!is_numeric($n) || $n < 0) {
              throw new \InvalidArgumentException('Precision must be positive number');
          }
  
          $this->int_precision = (integer) $n;
      }
docs: Set precision for all returned results.
  
  @param  integer $n Give number of digits for the mantis
  @access public
  @return void