From a previous posting by JE Mc Gimpsey
This will autonumber your invoice on opening. You can print 2 copies, and
save as the invoice number
Private Sub Workbook_Open()
Const sAPPLICATION As String = "Excel"
Const sSECTION As String = "Invoice"
Const sKEY As String = "Inv_key"
Const nDEFAULT As Long = 1&
Dim nNumber As Long
With ThisWorkbook.Sheets("Sheet1")
With .Range("H10")
If IsEmpty(.Value) Then
.Value = Date
.NumberFormat = "dd mmm yyyy"
End If
End With
With .Range("H10")
If IsEmpty(.Value) Then
nNumber = GetSetting(sAPPLICATION, sSECTION, sKEY,
nDEFAULT)
.NumberFormat = "@"
.Value = Format(nNumber, "0000")
SaveSetting sAPPLICATION, sSECTION, sKEY, nNumber + 1&
End If
End With
End With
End Sub