RagDyeR wrote...
It has to be more complex then just a "number of cells (entries)"
issue
Harlan, since A1:A65536 DOES work!
....

Not on my system. First, Excel *ALWAYS* replaces A1:A65536 with A:A.
Second, in a new worksheet, the following formula entered in B1

B1:
=SUMPRODUCT(--ISBLANK(A:A))

returns 0 rather than 65536. When I change the formula to

B1:
=SUMPRODUCT(--ISBLANK(A1:A65535))

it returns 65535. What results do you get on your system?

As for the formula in this thread, . . .

Ragdyer wrote...
...
And since ISBLANK accepts total references,

=LOOKUP(2,1/(1-ISBLANK(1:1)),1:1)
should work OK, right?
....

with A:A still all blank, I enter the following formula in B2.

B2:
=LOOKUP(2,1/(1-ISBLANK(A:A)),ROW(A:A))

It returns 1 to start with, not #N/A and not 0. If I change it to

B2:
=LOOKUP(2,1/(1-ISBLANK(A1:A65535)),ROW(A1:A65535))

it returns #N/A as expected (at least as I expect).

Reverting to the A:A formula, I then enter 9 in cell A11. The formula
*STILL* returns 1, not 11. What results do you get on your system?