Your number is highlighted. Tap anywhere on the screen to advance to the next number. If you pick a divisor (in either direction) then you advance. If you pick anything else it is game over. And if you aren't quick enough you will run out of time.
Touch a square. Solve the mental arithmetic question and slide to the next square. If you lift your finger or pick the wrong square you lose.
Expect more. I've done a few little things which haven't been released, but I'm also working with Swift and SpriteKit on some of new projects (I've also am/have worked professionally on some more conventional Apps).