Abacus Division

#abacus #abacuslearning #abacusmath #abacusforbeginners #soroban
Joe reviews subtraction, and long division using repetitive subtraction, a good technique for dealing with longer, multi-digit divisors.
Link to files used in this video: drive.google.com/drive/folder...
The Abacus Series Playlist: • The Abacus Series
A good quality soroban for adult-sized fingers (no relation to seller): tinyurl.com/2s42fpac
00:00 Introduction
01:10 Kojima's Soroban Books
01:55 Long Division
03:29 Example 3-digit Long Division on Paper
05:38 Pinwheel Calculator Division
07:04 Subtraction Overview
09:16 Subtraction Operation Problem Evaluation Procedure
10:06 Example Subtraction Problems
13:28 Division via Repetitive Subtraction
16:31 Another Pi Problem
16:54 Conclusion

[@joethesupercow]

Very helpful! Thank you!

[@lorensims4846]

Just as division can be done with repetitive subtraction, multiplication can be done with repetitive addition.
I'm convinced this is how computers do it. Binary numbers are not unlike abacus beads.

[@amartini51]

That's one way to do it, and is sometimes used on very simple CPUs - for example, the 6502 doesn't have multiplication, so you have to add and keep track in software to do multiplication. But most modern CPUs have dedicated instructions for multiplication, with corresponding circuitry that implements it.
In the olden days of computers, this would have even been a "budget" vs "power" option: Do you want to pay extra to have fast multiplication and division, done in hardware, or do you want a slower but cheaper computer?

[@benbaker9990]

For most engineering problems going to three decimal places is good.

[@NHGeneral]

for CNC, I believe 6 digits after the dot is considered acceptable.

[@LANCSKID]

Abacus Division … weren’t they a rock band from Arkansas in the 1980’s?

[@Joe_VanCleave]

They should’ve been! I’ll have to add that to my list of potential band names!