Well put together, but if you're going to make a math game, you ought to get the math correct... a bunch of others have pointed out the errors, but that's really the main thing bringing this submission down. Also minor glitches like on the left side if you're at the top of the squareish path the other tanks wont shoot you, unless you shoot them at the top of their path. Once one tank just blew up on it's own also, I don't know what that was about. And then I also saw two tanks get stuck together for a little while after one made a turn into the other. And the collision for the bullets on the tanks was not very good either.
Basically it looks like a pretty good game, the graphics and sounds are good, but it seems more like a beta form of the game.