"Dean" wrote in message
...
Thanks for your help, but I'll need a little more. Inside your formula,
you
have two hyphens and I don't know what that means.

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

Also, I thought I would need isna for a lookup function when it can't find
a
match, not iserror (though I imagine it's analogous). Please clarify.

Assume that I have entries in cells a6, b6, and c6; also a7,b7, and c7.
and
that the first three are 1, #n/a, and 2 and a7, b7, and c7 were 3,4, and
5.
Please write the exact formula for me. I'm thinking the result should be
1*3 + 2 *5 = 13.

Best to use a different tack for this

=SUMIF(A6:C7,"<#N/A")