how to auto increment a number each time i open the worksheet

i made a invoice and i want to have the number of invoice increment automatic
invoicenumber + 1

can someone help me

take a look at

http://www.mcgimpsey.com/excel/sequentialnums.html


In article <[email protected]>,
"fred rondak" <fred [email protected]> wrote:

> i made a invoice and i want to have the number of invoice increment automatic
> invoicenumber + 1
>
> can someone help me