private static function conversionTrackingCode($number, $barcodeIdentifier, $serviceTypeIdentifier, $mailerIdentifier, $serialNumber) {
        $number = bcmul($number, 10, 0);
        $number = bcadd($number, $barcodeIdentifier[0], 0);
        $number = bcmul($number, 5, 0);
        $number = bcadd($number, $barcodeIdentifier[1], 0);

        $temp = $serviceTypeIdentifier . $mailerIdentifier . $serialNumber;
        for ($i = 0; $i < 18; $i++) {
            $number = bcmul($number, 10, 0);
            $number = bcadd($number, $temp[$i], 0);
        }

        return $number;
    }