How do I Prevent a Crash When a Letter is Typed Instead of an Integer

So here's the problem, I have a variable called Denary which is an integer as I need to do maths with it. If someone using my program were to type in a
letter instead of a number it would crash. I would prefer to be able to post an error message but it crashes at the console.ReadLine so my knowledge leaves me unable to solve it.

Code:

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Console.WriteLine("Type a denary number between 0 and 255 to convert or press * to return to the main menu")
        Denary = Console.ReadLine 'Reads in the Denary Number

        If Denary > 0 And Denary < 255 Then
            Do While Denary > 0
                Binary(i) = Denary Mod 2
                Denary = Fix(Denary / 2) 'Divides Denary number by 2 and rounds dpwn
                i = i + 1
            Loop

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Use tryparse:

Code:

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If Integer.TryParse(Console.ReadLine, Denary) Then
  'Do stuff if it's an integer
Else
  'Do stuff if it's not an integer
End If

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Thanks!!

By the way, you wouldn't have to use Fix in there. You can just do this:

Denary = Denary \ 2

Note the difference between / and \. The latter is an integer division, while the former....is what you used and had to Fix.