Invoice Number = Now.Year & Now.Month & ????? Dim str = DateTime.Now.Year & DateTime.Now.Month.ToString("00") Sub Main() For i = 1 To 12 Console.WriteLine(GetAutonumber(i)) Next End Sub Public Function GetAutonumber(no As Integer) As String Dim strNum = no.ToString() Dim str = DateTime.Now.Year & DateTime.Now.Month.ToString("00") & New String("0", 5 - strNum.Length) & strNum Return str End Function