I didn't understand this game when I first played it, but after that I soon learnt how to play. To play the game, you have to click one of the number '1' on the top and then click one of the number '2' at the bottom. The number 1's have maths problems and the number 2's have the answers.
This game is very fun because it's confusing and makes you think a lot. You can change what's hidden behind the cards. Some of the additional changes are addition, letters and sounds. You can also change the amount of cards on the screen. There are 4x4, 5x5 and 6x6 options. 6x6 is the hardest and 4x4 is the easiest.
Here is a screen shot of the memorize activity.
I rule !!! =D