Rinne Tsujikubo. 13 years old Japanese girl

https://m.youtube.com/watch?v=jzrdKBGBhPU (at an Italian show).

Serioulsly there are NO European mental calculator who can beat her. She MUST participate in Memoriad World Cup. She’s amazing.

Soroban mental calculators have (I don’t know why) this great power. Look: answering right down an 7 digit by 7 digit multiplication is science-fiction!

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Practice my friend.

Still impressive though.


Truly amazing!
I have never seen anybody calculate so quickly.

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She’s a rising star in the world of mental calculation

I can imagine. I have never seen a 7x7 multiplication done so quickly.
However; I have some suspicion.

Here is the current world record doing 8x8’s:

His record is 10 8x8’s in 3 minutes 30 seconds or on average 21 seconds a piece.
So the speed difference is mind boggling.

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The current World record of 8 × 8 is by Marc Jornet Sanz.

Rinne told that she use SOROBAN techniques to do these multiplications so quickly.


yea, go practice for 10 years and try to compete with her today’s score

Why the hostility? You can reach her level too if you use good techniques and practice a lot. She is also not the first kid I’ve seen that can do this. She was not born with this ability either.

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I still wonder what the actual benefit of using a soroban over visualised numbers is. The data seems to indicate that there is a true benefit, in which case it reforms the world of mnemonics for skilled disciplines in new ways.

But really what is the benefit of moving beads instead of numbers? Especially if at high speed you no longer move them but instead place them in the right position just as you would numbers.

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