Imports System

Public Module Module1

    Public Sub Main()

    'Declare variables and arrays

    Dim ISBN(13) As Integer

    Dim CheckDigit As Integer

    Dim Total As Integer = 0

    'Populate first 12 digits of ISBN 

    For i = 1 to 12  

        Console.WriteLine("Enter digit number " & i)

        ISBN(i) = Console.ReadLine()

    Next i

    'Calculating the total

    For j = 1 to 12

        If j MOD 2 = 0 Then

            Total = Total + ISBN(j) * 3

        Else

            Total = Total + ISBN(j)

        End If

    Next j

​

    'Calculating the checkdigit

    CheckDigit = 10 - Total MOD 10

    If CheckDigit = 10 Then

        CheckDigit = 0

    End If

​

    Console.WriteLine("The checkdigit is " & CheckDigit)

​

    End Sub

End Module

​

​

' PSEUDOCODE

'

' INTEGER: ISBN[13], CheckDigit, Total

' Total <-- 0

'

' FOR i <-- 1 TO 12

'   OUTPUT "Enter digit number ", i

'   INPUT ISBN[i]

' NEXT i

' FOR j <-- 1 TO 12

'   IF j MOD 2 = 0 THEN

'       Total <-- Total + ISBN(j) * 3

'   ELSE

'       Total <-- Total + ISBN(j)

' NEXT j

' 

' CheckDigit <-- Total MOD 10

' IF CheckDigit = 10 THEN

'   CheckDigit <-- 0

' ENDIF

'

' OUTPUT "The checkdigit is ", CheckDigit

'

' OUTPUT CheckDigit

​