Dr Porter's Memory and Number Trainer

A memory and number trainer game from Dr James Porter (I have a Phd, albeit not in anything medical/neuroscientific).

Solve mathematical questions before the timer runs out while remembering the last number. Beat your high score while challenging your mental arithmetic and memory skills.

Touch and hold a square, solve the question and then slide to the next square. But one mistake (including merely taking your finger off the screen) and it is game over. Good luck.