Giving serial number with 4 digit long failed

Question

I have to get serial number that include Member that getting from the user and adding to the member serial number of 4 digit. if I got 888 the newMemberId will be 8880001, and in the next loop 8880002 and so on, the problem is when getting to index of ten I will get 888010 with this code. why?

while (dbNof.AllMembers.Any(x => x.MemberId == newMemberId))
{
    numerator++;

    newMemberId = Member + 
                  numerator.ToString().PadLeft(5-numerator.ToString().Length, '0');
}

Answer 1

If you want formatted output (at least 4 digits in your case) use formatting:

 newMemberId = Member + numerator.ToString("d4");

Or (string interpolation):

 newMemberId = $"{Member}{numerator:d4}";