October last year, I have introduced how to **represent numbers using the Japanese abacus**. In this post, I am going to teach you how to add and subtract using it. If you are not familiar on how to represent numbers in abacus, please read the first part of this series by clicking the link above. You have to understand the representation in order to follow the tutorial below.

Note that although abacus is not needed in the calculations below since it can be done mentally, calculations done in abacus in real life involve large numbers or even those with decimals. The examples below will only give you an overview of how calculations are made and some of the strategies used. Continue reading