N-back Sound's calculation

N-back calculation Brain Training
N-back, which is said of the brain training others, and give a huge impact on the working memory
In its N-back, large particularly influential "voice calculation"
In N-back traditional, remember numbers that appeared, it was only going to answer two, the number of front three.
Things that appear is not a number, this app, formula. In addition to that, we need to hear in the ear.
It can be said impact on the brain is greater.

If the 2-back of the (previous two) Example:
3 + 1 = 4
5 + 4 = 9
2 + 0 = ← answer the answer of the previous two for the first time here. In this case is the answer of the previous two "4"
7 + 1 = ← answer the answer of the previous two as well. In this case is the answer of the previous two "9"
↓ loop below