In MathInk, you control a white marble ball and bump it with black ink bubbles. Each ink bubble correspond to an arithmetic operation onto your score, and the goal is to maximize the score.
Ink bubbles can be "plus", "minus", "times", "divide", "negate" or "one-over" (divided by one). Each has its own merits and faults depending on the situation. The only exception is the "Red-Cross" bubbles which you should avoid.