I'm trying to sum a row if it meets two different criteria. Here's an
example. Here I would try and add column C if column A was 123 and column B
was group A. Or something similar. I tried to used sumproduct (reading
other responses to similar questions) but I get #NUM! error. Any ideas?

A B C
1 123 group A 5
2 456 group D 10
3 123 group B 14
4 456 group A 7
5 123 group C 6