There are 12 levels in each game and each level consists of 25 puzzles. Level 1 is the easiest while level 12 the toughest. Game starts with level 1 and moves to next level when all the puzzles are solved correctly. The default target is 24, you can change it to a dynamic target by going to settings. For continuous evaluation, turn the evaluation mode by going to settings.

Depending upon the level, you will be given 2 or 3 or 4 numbers, use given numbers and operations +, -, *, / and brackets (, ) to achieve the target.