Sheet1!$B$2:$B$9000 returns an array of Boolean values (True or False).

applying a math operation to these values converts them to numbers. the
first negative sign converts them to negative numbers and the second
converts them back to positive numbers.


Then sumproduct multiplies the arrays of 1's and 0's together - anywhere you
multiply 1 x 1 you get a 1 otherwise a 0. It then adds these up and gives
you the count of rows matching both positions.

you could do a single conversion for each column in this case since
multiplication of two negatives will produce a positive:

=SUMPRODUCT(-(Sheet1!$B$2:$B$9000=1),-(Sheet1! $C$2:$C$9000=14))

--
Regards,
Tom Ogilvy


"Todd S" wrote in message
...
Hi.

I've recently been introduced to the following formula
through Newsgroups:
=SUMPRODUCT(--(Sheet1!$B$2:$B$9000=1),--(Sheet1!
$C$2:$C$9000=14))

It works for my needs, however, I'm trying to understand
it for other applications.

What do the -- operators do? I've never seen them before
and can't find a reference.

Thanks!!

Todd