Sequential Numbering of Invoices when Printing

found some vb code on the net and got it working. Thanks to all

Private Sub Workbook_BeforePrint(Cancel As Boolean)
If ActiveSheet.Name = "Summary" Then Range("A1").Value = Range("A1").Value + 1
End Sub

Private Sub Workbook_Open()

End Sub

As long as your sheet is called Summary, the numbers in cell A1 change everytime you print (or print preview)