Subtraction Drills at Mac App Store analyse

Flashcard type drills for children recently introduced to subtraction. Select a number 1 through 12 and random numbers will be presented to subtract from. Four choices will be presented, select the correct answer and gain a point. If wrong, the incorrect answers are shown in red and the correct answer in green. For positive reinforcement, the character says things like "yes" and "I knew it" for correct answers. (There is no audio for wrong answers.)