I have a worksheet with data in the region C1:Z10.
I want to sum over everything in the region C1:Z10 which meets certain
criteria for columns A & B (more specifically: equal to 1).

Also, I don't want to create an extra column of sums for the region. All I
want is a formula.

I know I can use
SumProduct((A1:A10=1)*(B1:B10=1), C1:C10 + D1:D10 +...) , but that's too
clumsy.

What can I do? Suggestions are most welcome!