There might be writing on paper when it is a child and playing.
Such nostalgic play was made a game.
Addition between one digit.
Simply, it is usually the quite difficult in case of not being one.
If you master this "CALC MASTER"
Yous calculating ability might improve before one is aware, too.
More accurate, more faster.
Please aim at it.
And, please obtain the calculating ability more than now.
Aim (only addition).. CALC MASTER!