The 24 Game is an arithmetical game in which the objective is to find a way to manipulate four integers so that the end result is 24.
Each number can only be used once. Only arithmetical signs allowed are addition, subtraction, multiplication and division.
The goal is simple. your device will randomly generate the 4 numbers, and you need to solve it faster than your friend who is playing in the opposite position.
Younger kids can enjoy the game too even they only knows addition and subtraction.
This is a very good tool to help them on sense of numbers.