Hotchickbiker,

A simple way would be to use something like this, you could assign it to a
button, an open or before print event.

Sub Increase_Number
Sheets("Sheet1").Range("A1").Value = _
Sheets("Sheet1").Range("A1").Value + 1
End Sub
For other ways to do this or if this is going to be used in a temple have a
look here
http://www.mcgimpsey.com/excel/udfs/sequentialnums.html

And if you are new to macros you may also what to have a look here on
getting started with macros
http://www.mvps.org/dmcritchie/excel/getstarted.htm

--
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

"hotchickbiker" wrote in message
...
I am doing invoices in Excel. Each time i open a new one i need to put a
new
number in ....has anyone got a formula so i can avoid repeating numbers...
many thanks