Addition and Subtraction on the Soroban
of reading - words
How to perform addition and subtraction on the Japanese abacus?
You'll see: it's child's play. (Really! We assure you!)
In fact, there's only one method for performing these two types of operations. In this article, we will explain step by step in a simple and concise manner so you can do it too.
In our last article, Soroban: User Guide we presented how to represent numbers using the Japanese abacus.
In this new article, we will teach you how to add and subtract numbers using the Japanese abacus.
If you are not yet familiar with how to represent numbers on the Japanese soroban, we invite you to read the previous tutorial article.
Reminder: Soroban Topology
Note that even though an abacus is not necessary for the calculations illustrated below because they can be done easily mentally; real-life calculations on an abacus often involve large numbers or even decimals.
The examples below will only give you a glimpse of how calculations are done and some of the methods used.
Addition Basics
Example: 3 + 4
We cannot add 3 + 4 directly, so we move three 1-unit beads up and the 5-unit bead down in one place to represent 3 + 5. Since we added 5 instead of 4, we move one 1-unit bead back down (indicated by the red arrow).
This gives a final answer of two 1-unit beads and one 5-unit bead which equals 3 + 4 = 7.
Example: 7 + 6
We represent 7 by moving one 5-unit bead and two 1-unit beads. We cannot add 6 directly, but we can add 10 and subtract 4. So, we add a 1-unit bead in the tens place as shown in the following illustration.
The next problem is that we cannot subtract 4 directly. So, we can subtract 5 and add 1. Therefore, we return the 5-unit bead and move up a 1-unit bead on the same row.
Subtraction Basics
Example: Subtract 3 from 6
First, move the 5-unit bead down and a 1-unit bead up in one place to represent 6. We cannot subtract 3 directly, so we subtract 5 by returning the 5-unit bead and add two by moving 1-unit beads up. This gives a final answer of three 1-unit beads, which means the answer is 3.
Example 4: Subtract 6 from 13
We represent 13 by moving a 1-unit bead in the tens place and three 1-unit beads in the ones place. We cannot subtract 6 directly.
Let's break this down step by step:
- First, we subtract 3.
- Then we subtract 10, we add 9.
- Finally we subtract 2
So we get the result: 7
To complete this article, we invite you to watch the excellent video tutorial made by the channel Learn Through Play.
To Go Further
Once you (or your child) have mastered addition and subtraction on the soroban, why not go further by learning to master multiplication? Multiplication on the Soroban
We also advise you to check out our review of the soroban method, a complete training program to help you and your child learn the Soroban.
Finally, to be able to practice in the best conditions, we can only advise you to purchase a soroban.
