How to you selectively sum on a series of numbers?

[Guest]

I have a column filled with numbers, but I only want to sum up a few of them.

Let's say I have numbers filling A1:A10. Let's say I only want to sum up
the numbers located is A3 and A4. I'd like to ability to enter something in
the b column (e.g. "y" in cells b3 and b4) and have a formula that adds up
the values in the "A" cells that have a corresponding "y" in the "B" column.
This formula would allow me to selectively choose which cells needs to be
summed.

What is the best/cleanest way to write that formula? Thank you.

 

[Alex Delamain]

=SUMPRODUCT((A1:A10)*(B1:B10="y"))

this will add up all values in A where the value in B is "Y

 

[Guest]

Thank you!

 

[Frank Kabel]

Hi
see:
http://www.xldynamic.com/source/xld.SUMPRODUCT.html