RemReckon

RemReckon is a free, interactive and educational app, that can be used for brain exercise. You will see some random numbers for a short time and you have to remember them all. At the end you will see an operator, now you have to do the Operation on all the numbers and then give your answer to the result box.
For every correct answer, you will get 10 points and for every wrong answer, 5 points will be deducted. You will get 20 seconds to give an answer to every question. You can choose different difficulties from settings. The harder the difficulty, you have to remember more numbers.