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There is a geometric technique to perform multiplication of numbers.

enter image description here

But as the internet goes, it is hard to figure out who deserves the credit. What I've heard is

  • A mayan technique
  • From Vedic mathematics (possibly from the equally named book from Bharati Krishna Tirthaji)
  • Used in Japanese schools to teach kids about multiplication.

I would love it if somebody could shed some light on the origins of this technique.

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    $\begingroup$ I didn't want to imply that the way we learn it at school, say, in Europe is more complicated, but sometimes visualising a technique can help certain students grok something better. $\endgroup$
    – flq
    Aug 3, 2014 at 10:35
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    $\begingroup$ True. But seing how many think this is much easier and straight-forward without realising that it's the exact same thing always reminds me of how little the average person understands something so simple as "What is multiplication, really?" I see it as an indicator of how mathematics education all over the world must be wrong somehow if most people miss something like this, and it makes me angry at the world in general. I wrote what I wrote to vent out general anger, and it wasn't actually directed at you in any way. $\endgroup$
    – Arthur
    Aug 3, 2014 at 10:42
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    $\begingroup$ It's difficult to come up with a sicker way to teach kids multiplication. $\endgroup$ Aug 7, 2014 at 9:52
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    $\begingroup$ I think that the hypothesis that it's a Mayan technique can be ruled out. The MacTutor page on Mayan mathematics is pretty informative, and contains the statement, "We should also note that the Mayans almost certainly did not have methods of multiplication for their numbers and definitely did not use division of numbers." Some Mayan numerals do make use of sets of parallel horizontal lines, which may, at some point, have suggested to somebody a connection with visual multiplication, but I doubt there's anything to it. $\endgroup$ Aug 12, 2014 at 16:58
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    $\begingroup$ This question has come up on MSE before: here and here. $\endgroup$ Aug 15, 2014 at 8:18

2 Answers 2

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There is an accepted answer at History of Science and Mathematics:

It is a fun method but it appears to be very recent. It is characterized as Chinese, Japanese, Korean, Indian, or even Mayan method in various internet posts, all of them recent, and without attribution, naturally. The "ancient origin" story is most likely made up ...

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Let's make a table:

        300 +   20 +   1
      ------------------      ----> 10000 x        6  = 60000
200 | 60000 + 4000 + 200             1000 x    (15+4) = 19000
 50 | 15000 + 1000 +  50              100 x (12+10+2) =  2400
  4 |  1200 +   80 +   4               10 x    ( 8+5) =   130
                                        1 x        4  =     4
                                    -------------------------
                                                        81434

This is a very organized way to use the FOIL identity:

$$ (100x + 10y + z)(100a + 10b + c) = 10^4a +10^3(ay+bx)+10^2(az+by+cx)+10(bz+cy)+cz$$

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    $\begingroup$ This is a history of math question. It's not asking why the method works. $\endgroup$ Aug 9, 2014 at 3:23
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    $\begingroup$ Considering that I did not ask for this but is a useful information nonetheless, would you be ok with me including it in the question (with proper credits) and y removing this answer? $\endgroup$
    – flq
    Aug 13, 2014 at 20:17
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    $\begingroup$ what is "FOIL"? $\endgroup$ Nov 29, 2017 at 13:24
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    $\begingroup$ Also the Trachtenberg speed system puts an extra dot at intermediate places between each column to evaluate local square matrices.Believe it was from ancient Vedic maths; and there is also an unverified connection to the mayan civilization. $\endgroup$
    – Narasimham
    Jan 31, 2018 at 6:29
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    $\begingroup$ @RolazaroAzeveires it's an acronym for "First, Outside, Inside, Last" which is a mnemonic for multiplying two linear terms of the form $(ax+b)(cx+d)$ to make a quadratic which is taught in North American schools. It's basically a specialized case of the distributive rule for exactly this form which tends to confuse students the moments they try to multiply polynomials with more terms. $\endgroup$ May 15, 2018 at 14:19

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