title: Disabling letter input on Visual Basic
body: <p>So I have an assignment for a 101 class and I have no idea how to make it work. I have to disable letter input into a calculator, and using an IsNumeric string doesn't work right, any tips? Code is right here:    </p>
  
  <pre><code> Private Sub btnDoIt_Click(ByVal sender As System.Object, ByVal e _
                            As System.EventArgs) Handles btnDoIt.Click
      Dim strMSG As String = txtFnum.Text &amp; " + " &amp; txtSnum.Text &amp; " = "
      Dim intAns As Integer = CInt(txtFnum.Text) + CInt(txtSnum.Text) 
      lblAnswer.Text = strMSG &amp; intAns.ToString("N0")
      btnAgain.Visible = True : btnDoIt.Visible = False
  </code></pre>
  
  <p>Help is appreciated!</p>