I know I'm not who you replied to, but --
I had the dubious honor of teaching some 10-12 year olds a little math last week. (They didn't understand adding/subtracting negative numbers, couldn't do any long division, functions were an unknown quantity; but that's all beside the point.) I was trying to explain how, if you have say 12 x 30 and you can't do that in your head immediately, you can mentally break it down into 10 x 30 and 2 x 30, add the components, and voila. And then you can add harder and harder numbers depending on your capacity.
I'm not sure if that's a good "test"; it may even be too simple to have been in your book of tricks even though it is sort of a trick. But they couldn't do it. I was a smart kid so I tend to be a bit tough (not to their faces, of course) on children that age as far as what basics they know* -- am I unreasonable for thinking they should know how to do that, and for putting a good bit of blame on their teachers? Maybe we should push less "everyone's a winner let's do puzzles" and more "everyone can do basic mental math, so you need to learn it."
*the week before, I found out that many of them couldn't distinguish between states and state capitals i.e. "what's the capital of Missouri"; "Kansas?"