Is this a job for SUMPRODUCT? Or is it easier?

[Bob Phillips]

Ok. I see. I will need to find some documentation on what exactly 'ANDing' means.

See http://www.xldynamic.com/source/xld.SUMPRODUCT.html for a detailed explanation.

So, out of curiousity: Do you know how it does handle the 3rd array? Does 'ANDing' mean that Excel somehow detects the 3rd Array's shape and reshapes it to be compatible?

Excel doesn't detect the shape, you told it when you stated the ranges to test. Because it is multiplying the arrays, when it sees a horizontal range/array and a vertical range/array, it creates a matrix array result, which gets summed as per normal. That is why you cannot use the double unary form, because that is using SUMPRODUCT in its standard form, which will not multiply the different shaped arrays.