public static void Main()
Console.WriteLine("Hello World");
Console.WriteLine(GetIbanByAccountNumber("81280000743376001"));
private static string GetIbanByAccountNumber(string acctNo)
if (string.IsNullOrWhiteSpace(acctNo))
var bban = $"056{acctNo.PadLeft(19, '0')}";
var cx = decimal.Parse($"{bban}{cctemp}");
var sheba = decimal.Parse($"{cd}{bban}");
return sheba.ToString("IR000000000000000000000000");