Are you or your children terrible at the most elementary skills of math such as arithmetic? If that is the case or you just want to make it easier for memory I’d recommend the card game 24. I know they have an app version now. Can’t say I’ve played the app but I know the card game makes for intense competition. The game can be played alone or with a number of others. Regardless the goal of the game is to reach the number 24 with the 4 numbers listed. Each number is used only once and the end sum has to be 24. This actually builds a persons math skills so that for most basic math they can solve the problem in their head.