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Some weeks ago I saw in a blog post an anecdote of a mathematician who once gave a 'talk' (not really). The special thing was that he came directly to the chalkboard and started doing one computation that took several empty boards. Without saying a word during all the process (in fact all the presentation), when he put the last dot in the computation, the crowd started clapping excitedly.

I sort of remember and I wanted to come back to it to read it with more time, but I lost it. Now I have the doubt. Does anyone know about this anecdote? Who can this mysterious mathematician be?

Thanks!

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closed as off-topic by Namaste, ahulpke, ccorn, user223391, HK Lee May 9 '18 at 2:01

  • This question does not appear to be about math within the scope defined in the help center.
If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ If you just google your title, "mathematician who gave a presentation without saying a word", the first result is hsm.stackexchange.com/q/2105/3301, which has the answer... $\endgroup$ – AccidentalFourierTransform May 8 '18 at 14:28
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    $\begingroup$ This question is not about mathematics, within the scope defined in the help center. Instead, it is about the history of mathematics, and has an answer on HSMSE. $\endgroup$ – Xander Henderson May 8 '18 at 15:54
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    $\begingroup$ @XanderHenderson: The help center lists history of mathematics under the category "There are certain subjects that, while still on-topic here, might be better addressed by one of our sister sites:" Linking to HSM is appropriate; closing as off-topic is not. $\endgroup$ – Micah May 8 '18 at 19:00
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    $\begingroup$ I'm voting to close this question as off-topic because it has already been asked and answered at the historyOfMath.SE site: hsm.stackexchange.com/q/2105/3301 $\endgroup$ – Namaste May 8 '18 at 19:26
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    $\begingroup$ @XanderHenderson: I agree that the other answer (which I upvoted) is superior to the answer here (which I wrote in about five minutes right before going to bed). My disagreement is with your claim that being about the history of mathematics means that it is off-topic on MSE (e.g., see this meta post). If you want to claim that being a duplicate of a question on another site is close-worthy, I won't argue too much, but that doesn't make it off topic. $\endgroup$ – Micah May 8 '18 at 19:39
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Probably it was about Frank Nelson Cole's factorization of $2^{67}-1$. As Wikipedia says:

On October 31, 1903, Cole famously made a presentation to a meeting of the American Mathematical Society where he identified the factors of the Mersenne number $2^{67} − 1$, or $M_{67}$. Édouard Lucas had demonstrated in 1876 that $M_{67}$ must have factors (i.e., is not prime), but he was unable to determine what those factors were. During Cole's so-called "lecture", he approached the chalkboard and in complete silence proceeded to calculate the value of $M_{67}$, with the result being $147,573,952,589,676,412,927$. Cole then moved to the other side of the board and wrote $193,707,721 \times 761,838,257,287$, and worked through the tedious calculations by hand. Upon completing the multiplication and demonstrating that the result equaled $M_{67}$, Cole returned to his seat, not having uttered a word during the hour-long presentation. His audience greeted the presentation with a standing ovation. Cole later admitted that finding the factors had taken "three years of Sundays."

This MathOverflow question has a few more mathematical details, as well as a link to Cole's paper where he described his methods.

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    $\begingroup$ @Peter: How long would you estimate it takes you to compute $2^{67}-1$, though? $\endgroup$ – Asaf Karagila May 8 '18 at 9:10
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    $\begingroup$ @AsafKaragila: I can write down $2^{20}=1048576$ and $2^7=128$ from memory; then three long multiplications and subtract one. $\endgroup$ – Henning Makholm May 8 '18 at 9:31
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    $\begingroup$ @Peter: All in all, I think that doing that correctly, accounting for a style of rigor and checking which may vary from person to person (but seems high for someone who spent three years of calculating this), I could imagine this taking an hour. $\endgroup$ – Asaf Karagila May 8 '18 at 10:43
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    $\begingroup$ @PeterLeFanuLumsdaine: Maybe it was slow to write using chalk? Or he was building anticipation? $\endgroup$ – user21820 May 8 '18 at 11:34
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    $\begingroup$ Didn't someone at around the same time, or maybe in the late 19th century, spend several months manually factoring $2^{4n + 2} + 1$ for some numerical value of n around 20, after which someone pointed out to him that this equals $ 4 . 2^{4n} + 4 . 2^n + 1 - 4 . 2^n $, which is a difference of two squares? ;-) $\endgroup$ – John R Ramsden May 9 '18 at 14:15

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