Though once you set NumberFormat you don't have to use Format when

setting the value...



.Value = Format(nNumber, """A""0000")



could just simply be...



.Value = nNumber

I did change the code as you mention here.
Bingo, I noticed the new invoice number, A0020 was to the right side of the cell. So I did a couple more and found that A0020 + A0021 + A0022 = A0063.

Not that you would ever want to add invoice number (which are often not numeric) but I found this interesting.

Those little gremlins within Excel are always up to something.<g

This is about as far as I am going to go with this little project. There is no looming need on the horizon waiting for a solution. I'll archive it for future reference. Although, I did offer it to a poster looking to have a sheet that produced sequential "Project Numbers". Have not heard back from him.

Thanks for all the info, Garry.

Regard,
Howard