Hello, I’ve found on internet another method to do division on soroban but i couldn’t understand it

http://totton.idirect.com/soroban/Steve%20Treadwell/Easy_Division.pdf

I’m not sure what is the best way to do it. the method i’m using is the traditional method that i have learned in school, for example 485/5 I have to think about the number that I will multiply by 5 or less to get the number 48. This process takes me too much time while doing big operations to answer. Is there a faster way or a rule to follow? Thanks

I have written about division a lot on this forum. All of them are transferable to the Soroban.

Do a search.

In the pdf, the first example is 8710.8 / 11.9 = 732.

First I change

8710.8 / 11.9 o 87108 / 119

Put 87108 on the soroban.

Round 119 to 120. Easier to work with.

7*120 = 840, so focus on the leftmost 3 rods (871). Subtract 840 = 31.

We are working with 119 instead of 120, so for each 120 we subtract we add one

In this case we subtracted 7*120, so we add 7.

31+7 = 38.

The soroban now shows: 3808

3*120=360. Subtract 360 from 380 to get 20.

Add 3 to get 23

The soroban now shows: 238

2*120=240. Subtract 240 from 238 to get -2.

Add 2 to get 0.

We are done.

Answer: 732.

This, imho, is the fastest way to do it. I would love to hear other people tell me I am wrong and propose an even faster way.

Thanks a lot @kinma for your answer, i have read this method from your previous posts and comments, i just didn’t get it well but now i do yes it’s much better and easier. Thanks again!

@Kinma do you think this method is also good for a 5-7 years old child, I mean teaching soroban to children’s using this method of division.

I would teach 5-7 year olds in a visual way.

Start with visual pizza slicing.

Ask your child to divide a pizza or pie into 2,4,3 slices.

Observe what happens.

Then ask him to divide 10 items into 5 baskets.

Start with divisions that have no remainder.

Later ask him to divide 30 apples in 29 baskets.

Ask what to do with the remaining one.

great idea, thanks a lot

Back to the soroban.

In the second example in the pdf we see this example: 2908108 / 734 = 3962

The writers way of solving this works.

However; I would choose a different path.

In a lot of my posts about dividing I round the divisor. Here, with 734 I would choose a different approach.

3 times 734 is 2.202. This number is much easier to work with.

Here is how I would do the division on the soroban.

Put 2908108 on the soroban and focus on the 4 leftmost rods: 2908.

Subtract 2202 from 2908 to get 706. the soroban now shows;

3_________706108. Focus on 7061. 3 times 2202 is 6606.

Since 2202 is already 3 times 734, we are now dealing with 9 times 734.

Subtract 6606 from the left most 7061 to get 455. Add 9 to the answer rod.

The soroban now shows 39_________45508.

Focus on 4550. 2 times 2202 makes 4404. This is 6 times 734.

Subtract 4404 from 4550 (146) and move answer and dividend rods:

396________1468

In this last step 2202 is not useful, since 1468 = 734 times 2.

Subtract 1468 from 1468 to get a remainder of zero.

Move 2 on the answer rods.

Answer: 3962

thank you @Kinma for taking time to explain that. appreciate it a lot

my problem is here, how do i know that the number 3 is the right quotient for the 2202. i think i should practice a lot on multiplications first a lot.

You may know that 33 times 3 = 99 and close to 100. So, 34 * 3 = 102. Also close to 100.

For me, the very fact that a number ends in 34 leads me to try to find out if times 3 is an option.

If the divisor was around 750 I would have tried times two. Let’s say between 745-755.