Once I rearranged the cells in your format it did work.
Thank you,
PE

"bj" wrote:

try in C5
=if(isnumber(d5),d5+1, if (C40,C4+1,"otherwise"))

"PE" wrote:

I am struggling with getting this to work correctly.

If cell C40 and there is no number in cell D5 then I want the number
automatically put in C5 to be C4+1, but if D5 also has a number in it then I
want the number in C5 to be D4+1.

Example:
Cell C4 Cell C5
555 0
Cell C5
556
But if:
Cell C4 Cell C5
555 556
Cell C5
557

I don't know why I am having such a problem with this it seems like it
should be a simple task, but can't get it to work correctly.
Thanks,
PE