Imports System

Imports Microsoft.VisualBasic

Public Module Module1

    Public Sub Main()

        Console.WriteLine(Mod10CheckDigit(0011))

    End Sub

    Public Function Mod10CheckDigit(Counter As String) As Integer

        Dim i As Integer

        Dim TotalOdd As Integer

        Dim TotalEven As Integer

        Dim Total As Integer

        Counter = Trim(Counter)

        'get odd numbers

        For i = 2 To Len(Counter) Step 2

            TotalOdd = TotalOdd + CInt(Mid(Counter, i, 1))

        Next i

        TotalOdd = TotalOdd * 3

​

        'get even numbers

        i = 0

        For i = 1 To Len(Counter) Step 2

            TotalEven = TotalEven + CInt(Mid(Counter, i, 1))

        Next i

​

        Total = TotalOdd + TotalEven

        Mod10CheckDigit = 10 - IIf(Right(Total, 1) = 0, 10,

          Right(Total, 1))

​

    End Function

End Module