Last summer my brother and I bought a soroban (算盤), an abacus. My brother being fond of mathematical riddles, and me being fond of everything Japanese, made it a satisfactory bargain. The shop keeper (shop Hashi in Antwerp) told us that the object dated back from 1945. Although I’m not gifted with much mathematical intellect, we had some fun calculating bills and making up challenging sums for each other.
I’ve formed the number 808,284,629,037,219. Left hand should keep the abacus in place, right hand is used for moving the beads. You only use two fingers, thumb and index. You can do comma numbers too, just move the 1-10 row to the left.
The soroban consists of columns, representing decimals, and twee rows, the upper bead counting for five (godama 五玉), the lower five beads each for one (ichidama 一玉). The rules are explained on this site. At the beginning it’s a bit confusing but after some practising you can quicken up. This site has nice digital starter exercises.
Let’s compare with a Western abacus. I remember using one in first grade to calculate sums up to 20. But after the enlightening introduction of the arithmetic system, the abacus was left deserted in the corner of the class room. Because you need as many beads as the highest number you’re calculating with, it’s pretty useless.
|limit||never less than 100,000,000||(most of the time) 100|
|used by||children and adults||6-year old school kids|
|kind of calculations||+, -, :, x||+ and –|
Except for shops on the countryside, the soroban is often replaced by calculators and computers. But it serves another purpose now: competition. In school you can join the abacus club and aim for the nationals. Here’s a movie about a genius girl and her fellow soroban-clubbers. It’s Japanese spoken with French subs, but I think it’s quite understandable without English translation.
I thought we had the best part after the giant sum at the beginning, but they went on amazing me. They do sums three times faster than it takes with a calculator. They do sums just by imaging the soroban (“blind calculation” or anzan 暗算). They do sums while answering questions. And have I mentioned these are sums of successive three-digit numbers who appear on the screen for about a fraction of a second?
Facts For Fun
– The soroban derived from the Chinese Suanpan. The biggest visible difference is that the Chinese version has two beads in the upper row.
– In 1946 it was proved that a soroban is actually faster than an electric calculator.
– The instructions are recited in a tuneful voice. The numbers are represented as amounts of money, like Yen or Dollar.