Mathematics - Quick Calculatio

This is an APP tool for math training calculations.
It allows users to train their fast counting functions, including addition, subtraction, multiplication and division.
I think this is an interesting training. The user selects one of four options plus, minus, multiply and divide. The app automatically generates the 10 related questions you need to answer. And the user response accuracy, response time and completion will be finally displayed to the user, so that the user has a good understanding of himself.