Use one subroutine to handle the Keypress event for several textboxes.
Private Sub SeveralTextboxes_KeyPress(sender As Object, e As KeyPressEventArgs) _
Handles textbox1.KeyPress,textbox2,KeyPress,textbox3.KeyPress, textbox4.KeyPress
If e.KeyChar <> ControlChars.Back AndAlso e.KeyChar <> "-"C Then
e.Handled = Not Char.IsNumber(e.KeyChar)
If Not e.Handled Then
Dim num As Integer = _
Integer.Parse(String.Format("{0}{1}", _
If(DirectCast(sender,TextBox).Text = String.Empty, _
"", DirectCast(sender,TextBox).Text), e.KeyChar.ToString()))
If num > 11 Then
e.Handled = True
End If
End If
End If
End Sub