What is an abacus?

How an abacus works

An abacus is a frame of rods with beads that slide along them. Each rod is one place in a number — ones, tens, hundreds — exactly like the columns you use when you write a number down. A bead only counts when it is pushed against the bar that runs across the middle of the frame. Push it away from the bar and it is worth nothing again.

So instead of writing a number, you set it in beads. To add or take away, you move more beads. The board keeps the running total for you, which is what makes long chains of sums quick: there is nothing to write down and nothing to hold in your head.

The main kinds of abacus

Counting boards and bead frames have been used for thousands of years in many parts of the world, and several designs are still in use. The ones you are most likely to meet are:

• Soroban (Japan). One bead above the bar worth 5, and four below worth 1 each. Every digit from 0 to 9 has exactly one bead pattern. This is the abacus used in Japanese schools, in abacus competitions, and in every lesson on this site.
• Suanpan (China). Traditionally two beads above the bar and five below. The extra beads supported older calculation methods, but they also mean one rod can show the same value in more than one way.
• Schoty (Russia). Horizontal wires with ten beads each, usually with the middle two a different colour to make counting easier. There is no 5-bead; you slide beads one group at a time.
• Classroom counting frames. Ten beads per wire. Lovely for early counting and number bonds, but not built for fast calculation.

The Japanese soroban grew out of the Chinese suanpan and settled into its modern one-and-four layout during the twentieth century.

Why children learn the soroban

With one 5-bead and four 1-beads, a rod can show every digit from 0 to 9 and nothing more — there is exactly one way to show each digit. That tidiness is the whole point. Because every rod is predictable, the soroban can be worked with a small set of fixed moves instead of counting beads one at a time.

The key idea is complementary numbers: pairs that make 5 (like 1 and 4) and pairs that make 10 (like 3 and 7). When there is no room to add a number directly, you add 5 or 10 and take its partner away in the same movement. Learners call these pairs little friends and big friends, and once they are automatic, every digit becomes one confident flick.

Is the abacus still worth learning?

For grown-up sums a calculator is quicker, and learning the abacus is not about replacing one. What it gives a child is a concrete, hands-on picture of place value and of the number pairs that make 5 and 10 — ideas that sit underneath all later arithmetic.

Practised learners go on to anzan, picturing the beads in their heads and calculating with no board at all. Research into wider benefits, such as concentration or memory, is encouraging in places but mixed, so the fairest way to see the abacus is as an enjoyable and very effective way to get good at mental arithmetic, rather than a brain-training shortcut.

Where to start

1. Learn the parts of a soroban — heaven bead, earth beads, beam and unit points.
2. Read and set numbers on the board.
3. Learn which finger does what — thumb up, index finger for everything else.
4. Start adding and taking away.

No abacus at home? The free online abacus works on any phone, tablet or computer.