Only free tiles that are not covered or blocked on the right or left are allowed to be removed. Mastering Math Facts Mahjong will require math skills, strategy and a little luck. This a great game for kids learning and practicing math facts or for anyone just wanting a new type of Mahjong. This game offers lots of customizing options which keeps it fresh and interesting for kids. + Addition Facts + Subtraction Facts + Multiplication Facts + Division Facts + 24 layouts + 15 background pictures + 15 tile designs + Hint and Undo board options + 6 remove tile effects + 6 load tile effects