Private Sub Worksheet_Change(ByVal Target As Range)
Dim x
If Target.Count <> 1 Then Exit Sub
If Target.Column <> Range("L1").Column Then Exit Sub
x = Val(Left(Replace(Replace(Target.Value & Space(10), " ", ""), ".", ""), 10))
If IsNumeric(x) Then
If x > 99999999 Then
Application.EnableEvents = False
Target.NumberFormat = "00 00 00 00 00": Target = x
Application.EnableEvents = True
End If
End If
End Sub