Hi Iman, Thanks for your valuable efforts.
The problem should be in the "private static int[] SplitRoozMahSalNew(string farsiDate)" method :
...
if (strArray.Length >= 5)
num2 = int.Parse(strArray[4].TrimStart(new char[1]
{
'0'
}).Trim());
...
and more specific in:
...
TrimStart(new char[1]
{
'0'
}
...