Dear Jo
I would suggest to store the invoice number into an external file or a text
file in the same folder. The below solution increments the number everytime
you open; provided you save the workbook everytime you open.
If you are new to macros the set the Security level to low/medium in
(Tools|Macro|Security). 'Launch VBE using short-key Alt+F11. On the left
treeview right double click 'This Workbook '. Paste the below code...
Private Sub Workbook_Open()
Range("A1") = Range("A1") + 1
End Sub
If you would prefer to increment the number on each save, then paste the
below code.
Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
If MsgBox("Do you want to increment the invoice number", vbQuestion +
vbYesNo + vbDefaultButton2) = vbYes Then
Range("A1") = Range("A1") + 1
End If
End Sub
If this post helps click Yes