This is a very basic drill and practice where a question pops up and you answer it. Correct answers and incorrect answers get the same feedback, kids don’t get a chance to try again, and there are no visual prompts to help them get the right answer. The only real plus is that you can set the initial level. Based on the free part of the App (addition), I think the developers are kidding themselves that anyone would pay to unlock the subtraction and comparison sections (99 cents each).
Don’t bother. There are better apps free apps that offer more features and support.