I believe you will have to use a macro like this...

Private Sub Workbook_Open()
Range("A1").Formula = Range("A1").Value + 1
ActiveWorkbook.Save
End Sub

Insert this code under "ThisWorkbook". You will need to change the A1 to
the desired cell you want incremented. The "ActiveWorkbook.Save" may not be
necessary, depending on what you want. If someone opened the file and didn't
save, it would not record the change without that command.

"Jenner" wrote:

I am trying to increment a number by one every time the document is opened -
will I need to make a macro? I am new with macros and know not much about
them. Please can someone help - the original document is in word, but I'm
not sure if you can increment in word - it would be good if I could though -
I would rather use word then excel but if can't be done, excel will have to
do.

Thanks

Jenner