This appears to be a SUMIF:

=SUMIF(Sheet1!$A$1:$A$1000,Sheet3!A2,Sheet1!$C$1:$ C$1000)

Something like that. That assumes the "400" you wanted was in cell A2.
--
"Actually, I *am* a rocket scientist." -- JB

Your feedback is appreciated, click YES if this post helped you.


"Bobberjoe" wrote:

I am working in sheet 3 and want to look up all items that match column b on
sheet 1 and then sum up column c on sheet a and return that value in sheet 3
Here is a sample
Sheet 3

A B C
400 (look up all 400s(B) on sheet 1 and return the sum of all the
values in col C)
1000
1200
--
Kind Regards,
Bobby