It's quite a bit of reading, but it's very well explained he

http://xldynamic.com/source/xld.SUMPRODUCT.html

--
Kind regards,

Niek Otten
Microsoft MVP - Excel

"Vk" wrote in message ...
| When do we use -- (double minus) in a formula?
|
| Why it is not given in Excel-Help
|
| I have seen it being used with SUMPRODUCT inplace of *.
|
| Why -- is used and not *. What are the advantage"