Leave a cell blank if condition is false

Question

Other questions have touched on this and offered solutions that are not viable for a very large data set. I have a formula like the following across 9 columns:

Answer 1

Let NULL be the name of a cell that has "" in it, and BLANK be the name of a cell that is truly blank.

NULL is not truly blank; ISBLANK(NULL) will return FALSE. But note that '=' takes blank and null cells to be identical. So for any cell C1:

(C1="")
(C1=BLANK)
(C1=NULL)

will all return TRUE if C1 is truly blank OR if it contains "". (I find this simpler than using COUNTBLANK(C1)>0, which has been suggested elsewhere.)