Looks interesting, but I don't have an iPhone so can't give you a full review. From the description though I think I understand, what confused me a little more (I haven't had my coffee yet so it may just be me :) ) is the screenshots. The first shot shows an 8 about 4 or 5 numbers down and an 8 at the top. The one further down is green but in the next shot the one further up is green. The next shot shows a 3 (I understand how you got there) but then the next shot shows the 5. It seems like they are out of order in the screenshots. The swipe more to earn more points is unclear to me as well.

This may be an iPhone thing, but why even have the swipe? Why not just do the math and as the math is done correctly the bubbles disappear.

I like the concept though and it seems like it would be a really good game for learning/practicing math skills while also keeping your brain fresh.