How do I input for an automatic increment in a cell on Excel?

[Rissy]

I have made an invoice on Excel. I want the Invoice Numbers to increase by
one each time. How do I do a formula for this?

 

[Frank Kabel]

Hi
this is not possible with formulas. This would require VBA. e.g. see:
http://www.mcgimpsey.com/excel/udfs/sequentialnums.html