Private Sub Workbook_Open()
If ActiveWorkbook.Path = "" Then
[numero] = [numero] + 1
ActiveWorkbook.Saved = True
ActiveWorkbook.SaveCopyAs (Application.TemplatesPath & "Facture.xlt")
End If
End Sub

Private Sub Workbook_BeforeClose(Cancel As Boolean)
chemXls = Application.TemplatesPath & "Facture.xlt"
If ActiveWorkbook.Path = "" Then
Set wbk = Workbooks.Open(chemXls)
With wbk.ActiveSheet
.Range("numero") = .Range("numero") - 1
End With
wbk.Close True
End If
End Sub