Imports System

Imports Microsoft.VisualBasic

Public Module Module1

    Public Sub Main()

        Console.WriteLine("Enter an 8 digit credit card number to check if it is valid")

        Dim CreditCardNumber as String

        Dim numbersList(8) as Integer

        Dim total as integer

        CreditCardNumber = Console.ReadLine() 'Input number

        if(not (CreditCardNumber.Length = 8)) 'checks if number is 8 digits long

            Console.WriteLine("Please Enter An 8 digit number")

        else if(not (IsNumeric(CreditCardNumber))) 'checks if an actual number was input

                Console.WriteLine("Please Enter a number")

        else

            for i as integer = 0 to 7

                numbersList(i) = CreditCardNumber mod 10 'gets each digit and puts it in an array

                creditCardNumber = (creditCardNumber - numbersList(i)) / 10

                numbersList(i) = numbersList(i) * (i + 1) 'mulitplies each digit by its index

                total += numbersList(i) 'adds up the total

                'Console.WriteLine(total)

            next

            if((total mod 10) = 0) 'checks if total mod 10 is 0

                Console.WriteLine("This number is valid")

            else

                Console.WriteLine("This number is invalid")

            end if

        end if

        Main() 'Resets application

    End Sub

End Module