It's not for me. The app has an auto-finish option. It won't let you pencil down the wrong number [instead it lets you makes three mistakes and then it says you've failed. It also has special rounds and power-ups and stuff. All-in-all, there's a lot of extra stuff that gets in the way for me and makes the games too easy [even the hard ones]. I think I'mna find myself a different app. :/