How to solve this Soroban addition?


Here goes.

I’ll go into detail. Let me know what is unclear.

You already put 73 on the soroban.
We now add 59.
Start from left to right, so first add ‘50’.
The tens rod contains 70, and since 9 is the highest number we can put on the rod, we cannot add 5 by moving beads only on the tens rod.
We need to involve the hundreds rod. And we do this by adding one on the hundreds rod and simultaneously moving the top bead of the tens rod up, or subtracting 50. In one move adding hundred and subtracting 50 is also adding 50.


Last step: add 9.
Again we cannot add 9 by moving the right most rod.
We need to involve the tens rod also.
9 = 10 - 1, so add ten and simultaneously subtract one.
Try to do the tens and the ones in one move. One goes up and the other down.

Last we add 97. We start with the 9.
We cannot add nine by only moving beads on the tens rod.
We need to involve the hundreds also.
So add one hundred and subtract 10 (in one move).

Now add 7 and be done.
This time we can add 7 by moving beads in only one rod.
Move the top bead down and two beads below up - in one move - and the result is this:



The first thing is to thank you for your patience and your desire to teach me and everyone.

The second is to admire your way of teaching mental calculation. Thank you very much Kinma, I am very grateful


You are welcome!

I have written a lot about the soroban. Just browse through it and see if you can use anything:


Now I’m in trouble :confused: @Kinma

Ok, here goes.

We cannot add 7 to a rod that contains 6.
So we have to involve the 3rd rod from the right, where the hundreds are.
If we add one bead to the hundreds while at the same time move the top bead in the previous rod up, we have effectively added 50.
After that, all that needs to be done is adding 20 in the bottom part of the same rod (tens rod).


Next step:adding 3 to a rod that contains 3. We first add 5 by moving the top bead down.
Then subtract 2.



Ok, now I can add in Soroban. Thank you.

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