Structure Of Abacus

Last updated: 30 September 2026

“Abacus” is a term used for a primitive device, which made use of the fingers of both hands for doing arithmetic calculations. The Abacus instrument was needed by merchants to calculate the cost of their trades in countries like China, Japan, Korea, Thailand, etc.

Structure of the device

The evolvement in the structure of the Abacus can be divided into 3 stages namely: The primitive age, the Middle Age, and the Modern Age.

1. Primitive Age

The primitive Abacus initially had horizontal alignment when it was invented. Stones and pebbles were used as beads. The use of stones added to the weight of the abacus, limiting its mobility and often resulting in losing the track of the counts. Due to these complexities, the number and size of beads were reduced over a period.

2. Middle Age

The ancient Abacus was restructured by Sumerian, Babylonian, Chinese, Japanese, Indian, Greek, Egyptian and Roman civilizations during different ages. Therefore, Abacus has faced changes in its structure according to different cultures. Two of the most popularly known Abacus of this age are Suan Pan (Chinese) and Soroban (Japanese).

3. Modern Age

The modern-day Abacus is, a frame made up of either wood or metal, with vertical alignment of rods in which the bead moves while performing calculations. Soroban, the most recent Abacus modified by the Japanese is the one we make use of today. The student Abacus used in our classes has 17 vertical rods. The frame is divided into 2 decks: the upper deck and the lower deck. The upper deck has 1 bead on each rod, and the lower deck constitutes 4 beads in a single rod. The Abacus is often described as one of the earliest forerunners of modern calculating machines.

Parts of the Modern Abacus at a Glance

If your child has just received an Abacus, this small table will help both of you name every part of it. Once children know these parts well, they slowly start picturing them in the mind, which I have explained in our blog on how mental abacus training activates the brain's spatial number map. The beads are moved with the fingers of both hands, and you can also read why we use both hands to operate the Abacus.

To see how these parts are used for actual counting, read our post on how an abacus works. For a simple introduction to the tool itself, visit our page on what an abacus is.

Application of Abacus Today

The Abacus today, is used as a device that supports overall brain development also resulting in improved mental arithmetic skills. Join Mastermind Abacus, an Abacus training institute to develop your mental maths skills. You can begin with a free demo of our live online abacus classes.

Frequently Asked Questions About the Structure of Abacus

What are the main parts of an abacus?

An abacus has five main parts: the frame, the rods, the beam, the upper beads and the lower beads. The frame holds everything together, the rods carry the beads, and the beam divides the upper deck from the lower deck. Every calculation a child does uses only these five parts.

What is the bar in the middle of the abacus called?

It is called the beam. Some teachers also call it the dividing bar or the answer bar. It separates the upper deck from the lower deck. A bead has a value only when it touches the beam, so children read the answer by looking at the beads resting against it.

Why is there only one bead above the beam and four below it?

The upper bead stands for 5 and each lower bead stands for 1. With these five beads, a single rod can show every digit from 0 to 9, so no extra beads are needed. Fewer beads also mean fewer finger movements, which keeps a child's calculation neat and quick.

What are the small dots on the beam for?

These dots are called unit points. They are marked at regular gaps on the beam and help a child decide which rod will be the ones rod. Once that rod is fixed, the rods to its left become tens, hundreds and thousands, so bigger numbers stay in the correct place.

How is the Japanese Soroban built differently from the Chinese Suan Pan?

The Suan Pan has two beads in the upper deck and five beads in the lower deck on every rod. The Soroban was simplified over time to one upper bead and four lower beads. You can read the full journey on our history of the abacus page.

Does the number of rods change how an abacus works?

No. The working stays exactly the same. More rods only allow bigger numbers, or more than one sum, to be set at a time. This is also why the large abacus a teacher uses looks different from a child's. I have compared the two in our post on the student abacus and the teacher abacus.

Should my child learn the names of the parts before joining abacus classes?

It is not required. In the first few classes, the teacher introduces the frame, rods, beam and beads, and shows how to hold the abacus properly. If your child is curious, you can explore the parts together on our Virtual Abacus, which is available 24x7.

My child already plays with an abacus at home. When can proper classes begin?

The Mastermind Abacus programme is for children aged 6 to 14, in live online classes and at our centres. It has 10 levels of three months each, with two one-hour classes a week. For children aged 5 to 6, we have Lingo Bingo at our offline centres. You can also see what comes in the student kit.