People told me when I was younger that experts could use an abacus faster than an electronic calculator. That was certainly true about 20 to 30 years ago, but not so much anymore with the newer, faster calculators that have become mainstream (except with those guys which use a mental abacus). Nevertheless, it’s still nice to jump into the past about 50 years when everyone would have known how to use an abacus.
There are two main types of abaci: the Chinese suanpan, and the Japanese soroban. They are easily distinguishable. The suanpan has 2 beads on top, 5 on the bottom, and usually has 13 rows. The soroban has one bead on top, 4 on the bottom, and can have anywhere from 13 to 28 rows.
Most people learning abacus stick with the soroban, because of its simplicity. The Japanese technique associated with it allows you to add, subtract, multiply, and divide, as well as use some advanced techniques involving square roots and logarithms. Some of them can be very long, allowing for larger numbers to be used.
The Chinese suanpan is slightly different. It is not used much outside of China, except by Chinese immigrants to other countries. Because it has all the beads a soroban has, it can do all the Japanese techniques, in addition to traditional Chinese techniques, which are more difficult but can be a lot faster. The extra beads can be very distracting to someone using the basic methods, so a soroban would be more practical. (It’s not actually that hard. I started out with a quite ancient suanpan my grandma gave me, and I’ve learned to ignore the top and bottom beads.)
Although starting out will need some mental maths, much like doing equations on paper, as you get better, and once you memorise finger movements, using an abacus can become as practical as using a calculator if slightly slower. If you or someone you know is quite young (under the age of 10), consider enrolling them in an abacus school, and they could, with sufficient practice) learn to do the amazing mental maths shown in the video link above.
To learn how to use an abacus (anyone can learn, even if you’re 50!) visit this website. It demonstrates all the main Japanese techniques and has smaller tutorials on the Chinese techniques.