Study mathematics relaxing with a good game

This is a game that offers mathematical calculations, with progressive difficulty, it seems easy to answer all questions, but you will soon realize that it is not.
There are packages with a parachute that will give you time to think about it. You will have time to work out the appropriate response.
Obvious that there are many specific responses, many neighboring numbers, look similar, but only one will be the right one.

You can choose between
sums
subtraction
multiplications
divisions
of course you can also compose them together.

Then it checks a graph of your answers, try to get the maximum, and then it is sure that you put all else.