Public WithEvents tbx As MSForms.TextBox
Private Sub tbx_Change()
If tbx = "" Then Exit Sub
Dim n As Long, c As Control
n = Int(Abs(Val(tbx)))
If tbx <> n Then tbx = n
If n = 0 Or n > nt Then tbx = "": Exit Sub
For Each c In tbx.Parent.Controls
If TypeName(c) = "TextBox" Then _
If c.Name <> tbx.Name And c = tbx Then tbx = "": Exit Sub
Next
End Sub