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Using an Abacus/Multiplication
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Multiplication is, by definition, the addition of some number so many amount of times. Therefore, to multiply a number by a desired number requires the same principle.
To multiply:
Display the original number.
Think of desired multiplier.
If multiplier has more than one digit, multiply by digits separately
Add the original number however many times desired.
Move to the next digit and repeat step 4 if multiplier has more than one digit.
Example: (4×5)
4=4
0000-|-0
-0000|-0
4+4=4×2=8
0000-|-0
0-000|0-
8+4=4×3=12
000-0|-0
00-00|-0
12+4=4×4=16
000-0|-0
000-0|0-
16+4=4×5=20
00-00|-0
0000-|-0
Here is another example with one number having two digits: (5×2.5)
5=5
0000-|-0 (0)
0000-|0- (5)
0000-|-0• (.0)
5×2=10
000-0|-0
0000-|-0
0000-|-0•
5×0.5=2.5
0000-|-0
00-00|-0
0000-|0-•
10+2.5=12.5=5×2.5
000-0|-0
00-00|-0
0000-|0-•
External links
Multiplication on a Japanese abacus selected from Abacus: Mystery of the Bead