Down10 (Play & Learn! Series). When you add up the number blocks horizontally or vertically to equal 10, they will turn red and disappear. Blocks will fall down from above, so you have to erase the stacked blocks so they don't build up past the pink line. There are hidden problems in the app. You can try them if you complete some condition. Enjoy mental calisthenics with this app by competing with your friends or family members in the ranking or by simply working to increase your own score.