"JulieD" wrote in message
...
Hi Bill

for details on the SUMPRODUCT function itself check out
http://www.xldynamic.com/source/xld.SUMPRODUCT.html

and here's a link to a newsgroup post by Bob Phillips where he explains
the
double unary (--) and quotes a post by Harlan Grove on the subject
http://tinyurl.com/bv42x

But I used it, I didn't sue it :-).