On Jan 27, 7:21 am, Gatsby wrote:
And you're right- I don't understand what your formula means.

Did you want an explanation? If so, do you mean that you do not
understand my explanation (guess!) about formula having been entered
as text; or do you mean you do not understand the embellished formula
of the form if(and(...)...)?

At the risk of being presumptuous and overwhelming, I will attempt to
clarify both.

First, if you type A1+A2 (literally) into a cell, it will be treated
as text, just as if you had typed Total. Excel does not attempt to
interpret it, even though it looks like a "formula" to the human eye.
If you type =A1+A2 (note the addition of "="), it is treated as a
formula, and Excel performs the computation. I had conjectured that
when you copy-and-pasted someone's formula (which seems correct as
written), the leading "=" was missing one way or another. So
if(isnumber(...)...) was treated as text, not as a formula.

As for my embellishment, namely:

=if(and(isnumber(L14),isnumber(M14)), max(0, L14-M14), "")

it says: compute the max only if __both__ L14 and M14 contain numeric
values (either constants or the result of a formula); otherwise,
display a "blank" cell. The function AND() is true only when __all__
of its parameters are true.

HTH.