The object of the game is to make the number 24 from the four numbers in the puzzle. You can add, subtract, multiply and divide. Use all four numbers, but you can use each number only once. You do not have to use all four operations.
There are 1362 puzzles, which are all of the puzzles that can be solved to 24. There is a help button that will provide a solution for any puzzle.
One of my favorite puzzles is 1, 5, 5, 5. This is one of the harder puzzles, because it requires a fraction to solve.