Imports System

​

Public Module Module1

​

    Public Sub Main()

        Dim ISBN13(13), Total, CheckDigit As Integer

        Total = 0

        for i = 1 to 12

            Console.Writeline("Digit." & i & "")

            ISBN13(i) = Console.ReadLine()

            If ISBN13(i) >= 10 Then

                Do

                    Console.Writeline("Please enter a single digit")

                    ISBN13(i) = Console.ReadLine()

                Loop Until ISBN13(i) < 10

            End If

        Next

​

        for i = 1 to 12

            If i Mod 2 = 1 Then

                Total = Total + ISBN13(i) * 3

            Else

                Total = Total + ISBN13(i) * 1

            End If

        Next

​

        Console.Writeline("Total number of 1 to 12 digits is " & Total)

        CheckDigit = 10 - Total Mod 10

        If CheckDigit = 10 Then

            CheckDigit = CheckDigit - 10

        End If

​

        Console.WriteLine("Check Digit ISBN13(13) is " & CheckDigit)

        for i = 1 to 13

            Console.WriteLine(ISBN13(i))

        Next

    End Sub

End Module

​