Ken wrote...
I entered the formula as you listed them and I get a #N/A (Data Not
Available) error. . . .
....
"Harlan Grove" wrote:
....
A1006 [array formula]:
=MODE(IF(COUNTIF(A$1005:A1005,A$3:A$1002)=0,A$3: A$1002))
....

I did say array formula. That means you need to type the formula, then
hold down [Shift] and [Ctrl] keys before pressing the [Enter] key to
enter the formula. If the formula returns #N/A when entered as an
array formula, it may mean you don't have any other values that appear
more than once.