This is really polished and very well done too -was really fun trying to come up with the best way to determine which choice was right as fast as possible -usually went with just adding the last numbers and checking against the choices -but then it got harder and the last digits were the same and i was like uh oh -but still managed to go from there. Would like a little more time but the intensity and quick thinking was really satisfying -this is an awesome use of the limitation and a great educational game -fantastic work! :D