Where is that other post (author, subject, newsgroup).
It certainly would not be worth the effort of obtaining
the three C.F. possible per cell an evaluating each of them.
You can use this for a test.
Select all cells on the sheet (A1 as activecell)
and use this for the Conditional Formatting formula.
=ISBLANK($A13)
Sprinkle in a some content into some of the cells in column A.
Considering that it would take about 3 minutes per column
just to do a simply comparison on my computer for each cell.
I would take a lot more time and effort to obtain the conditional formats
and evaluate each to find out if True or False.
An example with just one Conditional Formatting formula would
take a long time by checking every cell. But if you used a
program or in this case a Worksheet Solution to calculate
what is actually being checked and how it affects the rest
could be as simple as:
=(35536 - COUNTA(A:A))*256