Luis, have a look here for ways to do it

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

--
Paul B
Always backup your data before trying something new
Please post any response to the newsgroups so others can benefit from it
Feedback on answers is always appreciated!
Using Excel 2002 & 2003

"LMiller" wrote in message
...
Hello!!
I´m trying to find a formula that changes the number in one cell, in a
consecutive way, using a macro button or every time the file is opened.

Example: The way a number of an invoice changes and doesn´t repeat itself
everytime you open the file or once you click on an assigned macro button!

Thank you in advance for your help.

Luis Miller.