A free program for Android, by Epsilon Development.

This app is very useful for learning numbers, addition, multiplication, and division. It is based on the same principle as most math games, and it gives you the same level of difficulty. The only difference is that it also includes a set of digits. The aim of the game is to solve the equations by using the digits and performing the mathematical operations. 

What’s more, it includes several levels, and each level is more difficult than the previous one. As you get better at solving the equations, the difficulty increases. This way, you can practice all the arithmetic operations without getting bored.