What you have to do is to remove some numbers from the equation by clicking on them.
It sounds simple but requires a lot of thinking.
The board sizes range from 5×5 to 8×8. There are also 3 levels of difficulty: 1-9, 2-4 and 1-19.
1-9 means the numbers to calculate will range from 1 to 9.
There are 2 game modes: Classic and Endless.
In Classic mode you can choose which board size and difficulty you want to play
In Endless mode you will be given a puzzle with random size and difficulty.
Your total wins in any mode is saved.