private function pad($padding = 1, $direction = STR_PAD_BOTH): string
    {
        return str_pad($this->number, $padding, 0, $direction);
    }
private function pad($padding = 1, $direction = STR_PAD_BOTH): string
    {
        return str_pad($this->number, $padding, 0, $direction);
    }
private function pad ( $ padding = 1 , $ direction = STR_PAD_BOTH ) : string { return str_pad ( $ this -> number , $ padding , 0 , $ direction ) ; }
Add padding to the number

@param int $padding
@param int $direction

@return string
Add padding to the number