using System;

using System.Text;

​

public class Program

{

    public static void Main()

    {

        DateTime dn = DateTime.Now;

        DateTime bd = new DateTime(1111, 11, 3);

        TimeSpan ts = dn - bd;

        double ddd = ts.Days;

        string datecode = ts.Days.ToString("000000");

        Console.WriteLine(datecode + ":::" + ts.Days.ToString());

        long x = 24;

        x *= 60;

        x *= 60;

        x *= 10000000;

        double dddd = (dn.Ticks * 1.356337 / x);

        Console.WriteLine(Math.Floor(dddd));

        Console.WriteLine(bd.AddDays(dddd).ToShortDateString());

        string r = "21" + datecode + GetLuhnCheckDigit(datecode) + "400";

        string rr;

        string cd;

        for (int i = 0; i < 10; i++)

        {

            rr = r + i.ToString();

            cd = GetLuhnCheckDigit(rr);

            Console.WriteLine(rr + cd);

        //Console.WriteLine(ByteArrayToString(enc.GetBytes((rr + cd).ToCharArray())).ToUpper());

        }

​

        r = "00" + datecode + "600";

        for (int i = 0; i < 10; i++)

        {

            rr = r + i.ToString();

            cd = GetLuhnCheckDigit(rr);

            Console.WriteLine(rr + cd);

        }

    }

​

    private static string GetLuhnCheckDigit(string number)

    {

        var sum = 0;

        var alt = true;

        var digits = number.ToCharArray();

        for (int i = digits.Length - 1; i >= 0; i--)

        {

            var curDigit = (digits[i] - 48);

            if (alt)

            {

                curDigit *= 2;

                if (curDigit > 9)

                    curDigit -= 9;

            }

​

            sum += curDigit;

            alt = !alt;

        }

​

        if ((sum % 10) == 0)

        {

            return "0";

        }

​

        return (10 - (sum % 10)).ToString();

    }

​

    public static bool PassesTheLuhnCheck(string Number)

    {

        var total = 0;

        var alt = false;

        var digits = Number.ToCharArray();

        for (int i = digits.Length - 1; i >= 0; i--)

        {

            var curDigit = (int)char.GetNumericValue(digits[i]);

            if (alt)

            {

                curDigit *= 2;

                if (curDigit > 9)

                    curDigit -= 9;

            }

​

            total += curDigit;

            alt = !alt;

        }

​

        return total % 10 == 0;

    }

}