If you know how to use an abacus, you can easily add and subtract without using the calculator.
Before people had calculators, mathematical calculations were made using the abacus.
And even today, some people find that using an abacus allows them to calculate problems faster than with a calculator. Let’s look at a simple step-by-step guide in which we explain how to use an abacus.
An abacus is like a manual calculator in which we have to slide beads representing their numbers.
This is a fairly popular instrument in China and Japan that has vertical beads, but we can also find abacus that have the beads in a horizontal format, which is how it is used in Europe, usually with ten rows with ten beads or balls each (different color), which is very easy to do as we explained.
Steps to using an abacus
- To use the abacus, you will see that the beads or balls can be moved from one side to the other.
- Depending on whether you move them to the right you will be adding units and otherwise you will be subtracting.
- In this way, all you have to do is take the abacus, place all the beads together to the left and count as you add or subtract.
- For example, if you have to add 9 + 4, you must have the first row, nine rows to the right. Then you can move four balls from the second row to the right and now count them all. The result will be the sum we have mentioned.
- Otherwise, the subtraction, the beads will be made by moving the balls to the left.
- Imagine they make you subtract 12-2, then you’ll move first twelve beads to the right and then you’ll move two beads to the left. The result will be the accounts you have on the right.
Using the abacus is easy and in fact is the best option for children to have a representation of the numbers when they learn to add or subtract, but we can also use it for operations that are somewhat more complex in which each row will have an increasing value, so that the last row has accounts with a value of 1.
The penultimate row will have accounts with a value of ten, the penultimate will have a value of 100 for each account, and so on until we reach the first row whose accounts will have a value of ten billion.
So if you are made to add 200 + 50, you can move two balls of the third level (starting from below) and five balls of the penultimate level (since each one has a value of ten).
This way, you only have to add the balls you have to the right and you will see how the result is 250 (if you have to add also units you have to use the last row).