Using an Abacus/Division

Division is practically the opposite process of multiplication. Division of a given number by a desired number involves the subtraction of the given number by the desired number a certain amount of times, and this certain amount of times the answer.

To divide:

1. display original number
2. think of desired number
3. subtract original number by desired number
4. add a bead to a separated row (recommended two above highest digit of original number), this is the counter row
5. Repeat steps 3-4 until original number is less than desired number
6. multiply original number by 10 and repeat steps 3-4 while adding one bead one digit less than counter.

Example: (15/4)

15=15      Counter
000-0|-0   0000-|-0
0000-|0-   0000-|-0•

15-4=11    1
000-0|-0   000-0|-0
000-0|-0   0000-|-0•

11-4=7     2
0000-|-0   00-00|-0
00-00|0-   0000-|-0•

7-4=3      3
0000-|-0   0-000|-0
0-000|-0   0000-|-0•

30-4=26    3.1
00-00|-0   0-000|-0
000-0|0-   000-0|-0•

... (6 more times)

6-4=2      3.7
0000-|-0   0-000|-0
00-00|-0   00-00|0-•

20-4=16    3.71
000-0|-0   0-000|-0
000-0|0-   00-00|0-•
           000-0|-0

... (4 more times)

4-4=0      3.75
0000-|-0   0-000|-0
0000-|-0   00-00|0-
           0000-|0-


Thus (15/4)=3.75

External links

• Division on a Japanese abacus selected from Abacus: Mystery of the Bead