N times before for Android
In the case of 3 times before example
1+1=2 <- memory
2+2=4 <- memory
3+3=6 <- memory
4+4= #2 <-The answer 3 times before and the answer of 4+4 is memorized.
5+5=#4 <-The answer 3 times before and the answer of 5+5 is memorized.
There is a random choice 1-7 times ago.
They are the gymnastics of the head.