This is what I implemented
String chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
private static String Increment(String s)
{
if (string.IsNullOrEmpty(s))
return string.Empty;
char lastChar = s[s.Length - 1];
string fragment = s.Substring(0, s.Length - 1);
if (chars.IndexOf(lastChar) < 35)
{
lastChar = chars[chars.IndexOf(lastChar) + 1];
return fragment + lastChar;
}
return Increment(fragment) + '0';
}