Private Const CharSet As String = "0123456789"

Private Sub Text1_Change()
    Dim Pos As Long, Str As String, Text As String
    Dim SelStart As Long
    With Text1
        Text = .Text
        SelStart = .SelStart
        For Pos = 1 To Len(Text)
            If InStr(CharSet, Mid(Text, Pos, 1)) > 0 Then
                Str = Str & Mid(Text, Pos, 1)
            End If
        Next
        .Text = Str
        .SelStart = SelStart
    End With
End Sub

Private Sub Text1_KeyPress(KeyAscii As Integer)
    If InStr(CharSet, Chr(KeyAscii)) = 0 Then KeyAscii = 0
End Sub