Abacus or 算盘 (suan4 pan2) in Chinese was a widely used computing machine before the invention of modern computers. The mathematics of abacus is called珠算 (zhu1 suan4) in Chinese. Although it has been used for thousands of years in businesses all around the world, abacus is losing to computers as a practical computation tool.
Then why should we learn abacus? First, it is fun. With some practice, you can impress friends with amazing computation skills. Second, abacus is a rudimentary computer. One can visualize the computer at work by pushing beads and learn some very basic concepts of modern computers.
We’ll teach here the Chinese abacus. There are other forms of abacus, but the principles are all the same. For more information, please Google for abacus.
A Chinese abacus instrument can be purchased from Amazon: Chinese abacus
1. Heaven and earth beads
The Chinese abacus has 2 beads in the upper deck (heaven beads) and 5 beads in the lower deck (earth beads).
Each heaven bead in the upper deck has a value of 5; each earth bead in the lower deck has a value of 1. Beads are considered counted, when moved towards the central bar that separates the two decks.
There are two ways to count 5: one is to move 5 earth beads up to the center; the other is to move 1 heaven beads down to the center.
There are also two ways to count 10: one is to move 2 heaven beads down to the center; the other is to move 1 earth beads in the column immediate left up to the center.
4. Any number
Once we understand how to count to 10, it is straight forward to count any integer in abacus. Just remember that the value for a bead is 10 times the value of the bead on its right; or is 1/10th the value of the bead on its left.
5. Unit and decimal point
You must be asking, where do I place the decimal point? You can start anywhere on the abacus, i.e., chose any rod as the unit rod. The earth bead on the unit rod is exactly 1; earth bead on the left of the unit rod is 10 and earth bead on the right of the unit rod is 1/10th, and so on.