C# Validate AMKA

gistfile1.cs

public static bool ValidateAMKA(string AMKA)
{
    double _numAMKA = 0;
    int sum = int.Parse(AMKA.Last().ToString());

    if (AMKA.Length != 11 || !double.TryParse(AMKA, out _numAMKA))
        return false;
    else
    {
        int iter = AMKA.Length - 1;
        AMKA.ToCharArray().Take(iter).ToList().ForEach(c =>
        {
            if (iter % 2 != 0)
            {
                int DigitTimes2 = int.Parse(c.ToString()) * 2;
                if (DigitTimes2 > 9)
                    sum += 1 + DigitTimes2 % 10;
                else
                    sum += DigitTimes2;
            }
            else
                sum += int.Parse(c.ToString());

            iter--;
        });
    }
    if (sum % 10 == 0)
        return true;
    else
        return false;
}