# How to use an Abacus

Diagram of a typical Chinese abacus set to zero - all heaven beads pushed up and all earth bead pushed down.

## Try the on-line Abacus

The Abacus utilizes a combination of two bases (base-2 and base-5) to represent decimal numbers. It is held horizontally with the smaller deck at the top. Each bead on the top deck has the value 5 and each bead on the lower deck has the value 1. The beads are pushed towards the central crossbar to show numbers. Working from right to left, the first vertical line represents units, the next tens, the next hundreds and so on.

So for example to show the number 9, on the first line, one heaven bead (top deck) would be moved down (representing 5 units) and 4 earth beads (bottom deck) would be moved up (each representing 4 units). To show the number 79, in addition to the beads in the first line used to make the number 9, one heaven bead would be moved down and two earth beads would be moved up on the second line, representing 5 tens and 2 tens respectively.

Addition on the abacus involves registering the numbers on the beads in the straight-forward left-to-right sequence they are written down in. As long as the digits are placed correctly, and the carry

1. On 15-Apr-2014, A.J wrote:
I like it!

2. On 15-Apr-2014, S.Y wrote:
Say

3. On 10-Sep-2013, Anonymous wrote:
can anyone tell me why it is called the heaven and earth beads
• On 11-Sep-2013, Peter Tong replied:
I could only guess that the ancient Chinese like to name things that is place on the top "heaven".

4. On 16-Jul-2013, Anonymous wrote:
i’m a math teacher and I find it hard to use it... I believe it’s hard for first timers.
• On 06-Sep-2014, 4B replied:
An abacus isn't a calculator where you just punch numbers. Think of it as a computer game--you have to learn how to play it!

5. On 27-Jun-2013, Ray wrote:
I have an Abacus given to me, that looks exactly like the one in the photo on your page. The third row in from each end, is a copper (?) rod which is thinner than the others. The others appear to be wood, or bambo. Are the copper rods only for structure, or do they have another purpose? My Abacus also has the same exact brass (?) corner brackets and the exact ornate brass (?) brackets that hold the divider bar in place. Could my Abacus be old? I do not know its origin.
• On 06-Sep-2014, 4B replied:
Late to reply but your comment (antique appraisal) really isn't relevent to the discussion on how an abacus works.

• On 27-Oct-2014, Anonymous replied:
what does that have to do with how to use an abacus ??

6. On 01-Oct-2012, Anonymous wrote:
Just to clarify; when using the abacus does one start from the far right side of the abacus or the far left side? Thank you.

7. On 19-Sep-2012, Anonymous wrote:
thx very much i never really fully comprehend it but now i do

8. On 13-Sep-2012, Sabrine wrote:
This information was very useful because it explained how to use a Abacus. so thanx
!

9. On 11-Sep-2012, Bryan wrote:
i need to know how to add or subtract or divide or multiply with an abacus!!! so this was no help. :(

10. On 28-Jun-2012, SAIRA KHAN wrote:
HELLO

you have shown working of abacus by table which is difficult to understand.