I'll leave other folk to answer your question, but please don't use *--
If you are doing arithmetic with the multiplication operator, the double
unary minus isn't doing anything for you, and will just cause confusion.
--
David Biddulph

Steve wrote:
I am working with hourly readings and making a monthly summary. I am
looking for a formula that will find the maximum of all of the hourly
values for each month and return the date/time of that peak. The
date time is broken into components so my data looks like:
Col C Month
Col D Day
Col E Hour
Col N Total
I know I need sumproduct and I am using
=sumproduct((D2:D8785)*--(C2:C8785="month in
question")*--(max(C2:C8785="Month in Question")*--(N2:N8785))). Im
guessing I either have an extra or missing -- and Im not sure about
ctrl-shift-enter. "Month in Question" is changed based on actual
reporting month and is not a named range. Also what modification
would I make to return one of the one of the individual values in col
F-M for that same peak date/time.

Thanks