A free program for Android, by Math Master Studio.

The Math Master app will help improve your capacity for logic. Finding regulars buried in numbers is the game’s goal in order to find the answer. Playing this game improves your capability to observe, rational thinking, innovative thinking, and mathematical understanding. This is a very helpful app, especially for children. At an early age, they can check this and parents can assist their kids in using this app. This is also a good way for families to bond. 

There is always one that will be challenging for you because puzzles are arranged by difficulty. So be ready for each level and have fun.