The Korean king's magic square: a brilliant algorithm in a k-drama (plus geomagic squares)

A double feature on magic squares featuring Bachet's algorithm embedded in the Korean historical drama series Tree with deep roots and the Lee Sallow's geomagic squares.
00:00 Intro
02:52 Part 1: The king's magic squares
09:40 Proof
18:22 The order 5 and 7 magic squares
19:17 Part 2: Geometric magic square
30:59 Thanks!
The Korean historical drama Tree with deep roots is available here www.viki.com/tv/1585c-tree-wi... All the magic square action takes place in episodes 1 and 2.
Episode 1: the king's study with magic squares at 33:17 again at 42:00 (father "simplifies" magic squares)
Episode 2: lunchbox action starts around 46:00 then again at 58:39 (the AHA moment)
Lee Sallows's book: Geometric magic squares, Dover (2013)
His website: www.leesallows.com
His comprehensive online gallery of stunning geomagic squares: www.geomagicsquares.com/
Nice write-up about the 33x33 magic square in Tree with deep roots: tinyurl.com/mszxrf2w
Wiki page on Claude Gaspar Bachet de Méziriac: en.wikipedia.org/wiki/Claude_...
Eduard Lucas 3x3 magic square equation: en.wikipedia.org/wiki/Magic_s...
An app by Ilm Narayana that demonstrates the king's method for magic squares up to order 33 (thank you very much Ilm for accepting my coding challenge:) editor.p5js.org/ilmnarayana/f...
Bachet's magic square algorithm write-up / bachets-magic-square (this article by Humanicus features the same proof that I present in this video)
Here is a magic square from an old Chinese manuscript en.wikipedia.org/wiki/Magic_s... Among other things they are writing from top to bottom which would also have been done in Korea at the time. In fact, in the drama the tech support ladies can be seen writing from top to bottom. So that's a bit of a blooper when it comes to the writing on the tiles. A few other minor issues are discussed in the comments. What's also interesting here that they went for a 33x33 magic square and 33x33=1089. 1089 is a four-digit number and all the tiles are only labelled with three numerals. How did they write 1089 and still make sense? :) Why not use a 31x31 magic square? 31x31=961.
For the second method for building odd order magic squares check out this link: en.wikipedia.org/wiki/Magic_s...
Some bugs:
- at 18:48, there is no green circle on the 2nd row 3rd column square.
- at 23:00, I should have said: take any 3 or more of the numbers that add to 15, then the corresponding pieces combine into the 4x4 with the bite (important because, for example, 7 and 8 don't work).
- at 28:20 one of the pentominoes is a hexomino :)
Today's music: Ardie Son - Counterparts
Today's t-shirt: 31415... Cannot remember where I found this t-shirt.
Enjoy!
Burkard

[@thicknavyrain]

You know it's going to be a great video when you're only one minute in and you've already seen three excellent results.

[@landsgevaer]

You know that it is going to be a great video when it is Mathologer, you have just started the first second of the video, and you've already seen three comments pointing out how exceptional the video is. I am confident that I am going to agree with your assessment.

[@craigdupree1687]

You know it's going to be a great video when it's posted by Mathologer.

[@neonblack211]

you knoiw its going to be a great video when its mathologer

[@gracenc]

You know it's going to be a good video when the intellectuals watching the channel make idempotent statements just to emphasise how great the video is. No judgment, @neonblack211 :)

[@kesotone]

KZbin needs a super like button for this level of content. Bravo Mathologer!

[@KNemo1999]

Oh, that's what an empty lunch box means. I just thought my mom was a little absent-minded. But this makes so much more sense.

[@TheShadowOfMars]

Empty lunchbox = you don't need any food = you're a dead man

[@frankharr9466]

I hope she wasn't too disappointed and decided better of it.

[@nhuthuynhminh2603]

💀

[@freewheelburning8834]

either absent-minded or just a socialist either way I think Karl Marx would approve

[@Axman6]

Oh no…

[@jonpopelka]

There’s a reason that the all-time mathematical greats like Euler, Ramanujan, Laplace, and Fermat were fascinated by magic squares and other patterns! It’s the knack and habit of recognizing those underlying structures which led them to some of the greatest insights and advances in mathematical history. THIS is why it’s so important to teach our kids more than rote memorization of numbers, facts, tables, and theories; we need to teach them how to see them as patterns which lead to other patterns within even further patterns. People with the gift of innate intuition about patterns are the people who change the world.

[@Mathologer]

What's also interesting is that a LOT of people who are into maths look down on things like magic squares not realising how important these little things are in the grand scheme of things :)

[@islandbuoy4]

my gift to the world is pointing out the OBVIOUS associations between the proof the fake Pitagoras used for the right triangle theorem, the 3x3 Lo Shu magic square, the 5x5 Rotas Sator palindrome and the 12,000+ year old 2D CHIRAL swastika ... but the ignorant do not want to acknowledge this insight due to WW2 crimes committed against humanity ... the truth is genius, hidden in plain sight and a bitter pill to swallow ....

[@tcadityaa]

@J Lund wtf

[@zoomlifecoach]

@@Mathologerhi mathologer I love your videos thank you for making such great content

[@twitter.comelomhycy]

This is why 바둑/圍棋/囲碁 is important to teach to al children.

[@ytrichardsenior]

Dear Mathologer. I can see how much work goes into these video's, but please never stop doing them. When I was a child I remember asking myself why we didn't have a TV channel that just showed educational programs. You (and a handful of others) make youtube what it can and should be. Thank you.

[@DarknessGu1deMe]

18:28 mentions the general rule of filling odd magic square we were taught in China in primary school. The rules was written as so: 一居上行正中央，依次斜填切莫忘 上出框时向下放，右出框时向左放 排重便在下格填，右上排重一个样 Translation: 1. put 1 in the middle of the first row 2. fill next consecutive numbers diagonally 3. when going out on the top, put into the bottom row 4. when going out on the right, put into the left column 5. if the square is occupied, put into the square below 6. if going diagonally on the top right, the same rules applies

[@Mathologer]

Very nice. The Chinese text looks like it may rhyme. Does it?

[@DarknessGu1deMe]

@@Mathologer It does rhyme! and it is deliberately written in the form of seven-word-poem (much like the solution poem to the Chinese remainder theorem). On this same topic, there's another, much more ancient (and famous) "poem" on just the 3x3 magic square: 九宫之义，法以灵龟，二四为肩，六八为足，左三右七，戴九履一，五居中央 Translation: """ The way to fill a 9-square palace, is to imagine a turtle (back): 2 and 4 as the shoulder, 6 and 8 as feet, 3 on the left, 7 on the right, 9 as hat, 1 as shoe, and 5 in the middle """ This text came from an ancient manuscript, that says these numbers/pattern comes on a turtle, and it's a sign of miracle. I guess that's part of what you said in the video: some people think magic square is truly magical.

[@Mathologer]

@@DarknessGu1deMe That's great. Thank you very much for sharing this with me :)

[@howareyou4400]

@@DarknessGu1deMe There is a much simpler version by 杨辉(1127~1279) 九子斜排，上下对易，左右相更，四维挺出。 Which translates roughly to: 1. arrange the 9 numbers "along the diagonal direction" (3 X 3 tilted square) 2. switch top and bottom 3. switch left and right 4. "stick out" the 4 corners.

[@nidalapisme]

@@DarknessGu1deMe I think the poem ever showed up in 1994 chinese tv series "Legend of the Condor Heroes" when the main character was trying to solve the 3x3 magic square puzzle to open up a door to a secret place. The female character solved the puzzle whilst citing the poem after she saw a turtle nearby. I remember she put 5 in the middle square as her last move to complete the puzzle. cmiiw.

[@nanamacapagal8342]

8:24 The magic constant is sum of all numbers in the square divided by the number of rows. For those looking for a concise formula: it should be (n²(n²+1)/2)/n or simply n(n²+1)/2. Plugging in 33 will give us the magic constant of 17985. 18:48 Go up-right one space. If you exit the board, wrap around to the other side. If you run into a space already filled in, drop straight down one space instead.

[@Mathologer]

That's it :)

[@karmageddon9136]

You're right on. You know the sum of each row, but how do you figure out the individual numbers? This video showed an interesting technique.

[@dan-florinchereches4892]

I was using another way of reaching the solution. Is there a reason to add every single number together? Since we have an odd number of pieces intuitively the middle number multiplied by the number of rows is going to be the only answer to the question pertaining the sum. This is immediately obvious because if a number larger than this was the answer then there necessarily exists another column/row which is lacking. Average value is (n^2+1)/2 and we can multiply by n, reaching the same conclusion. I love your algebra though.

[@nidalapisme]

I think it's called the Siamese method for solving magic square in that fashion. cmiiw.

[@riccardosarti3234]

Conjecture: the number at the center of an odd magic square is always the middle number in the list, i.e. the average number in each cell i.e. (n^2+1)/2 (which is an integer as n is odd). Can you prove it? If this is false, can you find a counter-example? Also, given n odd, how many magic squares do exist (with the equivalence relation given by the trivial horizontal/vertical reflections and 90° rotations)?

[@jeff__w]

I can't believe you mentioned _Tree With Deep Roots._ Knowing next to nothing about Korean or Korean, I stumbled onto that drama around 2011 and was intrigued by the story of Hangul woven into it. I learned to read it and eventually became somewhat proficient in Korean, all because of a random K-drama! Funny how those things work.

[@Mathologer]

I liked the drama but not the way it ended :)

[@jeff__w]

@@Mathologer oh, yeah, I forgot the ending. By around the midpoint or so it began to get a bit ridiculous, I thought, but I did watch it till the end. (And it _did_ get me into Hangul and Korean quite unexpectedly.) _Edit:_ The original comment should read “Korea or Korean.” Oops!

[@kmjohnny]

So this is why sudoku named one of their optional rule as magic square.

[@JCOpUntukIndonesia]

And turns out, there is a 3D equivalent for magic squares called a magic cube. Going beyond 3D, we have magic hypercube. How can I never hear of this before? I love that the well-known classic problem has a lot of different variations to tinker about. Especially when each has a unique approach to the problem. The wonder of math always amazes me.

[@FLScrabbler]

Reminds me of wordsquares that are cubed. For instance "CUBE" can be squared like this: CUBE UGLY BLUE EYES But then each of those other three words can be made into a wordsquare as well, which is then considered to have cubed the word "cube": UGLY GLUE LULL YELP BLUE L### U### E### etc.! (I'm sorry, I have forgotten the rest...)

[@SgtSupaman]

@@FLScrabbler , I've tried working out the rest of this cube from what you've provided, but I am unsatisfied with the set up. The cube properties applied to the used words duplicates "lull" as stemming from the L in "ugly" and the L in "blue", and then duplicates "yelp" as stemming from the Y in "ugly" and the Y in "eyes" (I don't know if it is possible, but I would think a cube with unique words at every step would be more interesting). Then that sticks you with a 'ul' to start a word with, which is a tough fill. Here is the final result I came to: CUBE UGLY BLUE EYES UGLY GLUE LULL YELP BLUE LULL ULTS ELSE EYES YELP ELSE SPED

[@FLScrabbler]

@@SgtSupaman Very nice! Well done..!

[@MichaelDarrow-tr1mn]

because if you try to make a magic cube it doesn't work.

[@PC_Simo]

@@SgtSupaman Very nice. Also; if you allow proper names, then one possibility would be to replace ”ULTS” with ”ULAM”, and ”ELSE” with ”ELMO”. 😌👍🏻

[@jacoboribilik3253]

The proof sketch was brillianty displayed. That "aha" moment you experience when it finally sinks in is priceless, almost addictive.

[@johnchessant3012]

Neat proof of an amazing result! I'll have to watch that show because it sounds like the best use of math in a film / tv show ever. Also, nice pi shirt!

[@ahcuah9526]

It's not a T-shirt, it's a Π-shirt! (Is there something encoded in blue vs white dots?)

[@jonathanrichards593]

@@ahcuah9526 It looks as if every third digit is in white; I'm unaware of any significance in that sequence of numbers, but with Mathologer I just *never* know!

[@kk-wl2yg]

The level of video and animation is amazing. This is a huge and talented work! СПАСИБО БОЛЬШОЕ 👌

[@johnchessant3012]

My favorite fact about the Dürer magic square: it was completed in the year 1514, and in the middle of the bottom row you can see it says 15 14. The only similar example I know of is the Basel problem, posed in 1644 whose solution is pi^2/6 = 1.644... However, sources differ on whether it was first posed in 1644 or 1650.

[@Mathologer]

Actually the Durer square has a couple of other magic properties. In particular the four 2x2 blocks in the corners and the one in the middle also all add to the magic constant. Sadly these extra properties are not replicated by the geomagic counterpart :)

[@FLScrabbler]

@@Mathologer This property is the reason why Dürer was able to put the year in middle of the bottom row after generating the MS by inverting the diagonals: The two central columns were swapped without affecting the magic constant...

[@stevereckamp3152]

Wanted to generalize the formula for the magic sum. for an n x n magic cube, I noticed that the sum of the "columns" are just Σk (k=1..n) and the sum of the "rows" is nΣk (k =1..n) - n² (the equivalent of nΣk (k =0..n-1) . That means the sum of all of those unique values (and the magic sum of the square) = Σk (k=1..n) + nΣk (k =1..n) - n² = (n + 1) nΣk (k =1..n) - n² substituting n/2(n+1) for Σk (k =1..n) = n/2 (n+1)² - n² And some math autopilot = n/2 (n² + 2n + 1) - n² = n³/2 + n² + n/2 - n² magic sum of n order magic square = *n/2 (n² + 1)* S₃₃ = 33 * (33² + 1)/2 = 33 * (1089 + 1)/2 = 33 * 1090/2 = 33 * 545 = *1795* _Also note it will always be an integer because n is odd so n² is odd and (n² + 1) is even and divisible by 2._

[@SmartHobbies]

I love seeing Magic Squares used in Sudoku variants. Thanks for sharing.

[@cparks1000000]

It's always exciting when these come out!

[@daviddilaura4614]

As always: beautifully and clearly presented.

[@luxinvictus9018]

this channel is absolutely fantastic!

[@_abdul]

Love the Pi Tshirt, Nice Visualisation of Pi.

[@yomrcheng]

Your animations were amazing, I would have never been able to visualize this without your excellent animations. I was truly impressed, I learned a lot thank you!

[@wegwang7795]

It really makes me glad to see more China-related or Eastern Asia-related videos here!

[@Peccomment]

Your videos make may days… everytime… thank you.

[@FrankHarwald]

This is honestly the best video on magic squares on KZbin & the best comprehensible video on the topic I've ever seen. SUPER! B)

[@crigsbe]

Your videos are just beautiful ! ❤ CONGRATULATIONS ! 🎉 🎉🎉

[@alwysrite]

you are a genius and such a good teacher who is willing to share to the world, thankyou

[@PC_Simo]

Of course, a nice feature of the 3*5 magic rectangle is the fact that it quite well approximates the golden rectangle, considering the size of its denominator.

[@richardschreier3866]

Thanks for crafting such a lovely video. The hours spent in photoshop yielded a beautiful result, and the delightful subject matter made the video a joy to watch.

[@Piffsnow]

Mathologer never disapoints. I'm so glad to know this channel.

[@Quazgaa]

I was proud of myself for decoding your shirt 🧐 Not everyone can be a genius

[@jeanconstant]

Fascinating. Thank you for the clarity of the demonstration & the inspiration that comes with it!

[@Mathologer]

Glad you enjoyed it!

[@Carlos-qz7ul]

I'm blown away by the amount of work necessary to build such a video, besides the knowledge and the insight needed 🙉

[@avoirdupois1]

I loved playing with the cube puzzles like those when I was a child. The manipulation of the pieces, not just in hand, but also in my mind lead me to a greater understanding of mechanics, physics, and engineering. Thank you for this great video!

[@far2ez]

I'm a natural-study at Math. Have been my whole life. I could derive and integrate common polynomial and other typical calc1/2 problems mentally when I was like 14. School couldn't keep up, though, and the internet wasn't meaningfully around yet. As a result, I found it boring as I got older, and I moved into comp sci instead, working at a FAANG company living the easy life. But you really bring out the romance in math out of me. I genuinely never found any appeal in any other mathematician on KZbin (even though I respect them and what they know, they just don't resonate with me). But your work is really incredible -- had you been doing your thing 20 years ago, I would've gone into math for sure. Keep up these videos. They are really so good.

[@bloodypommelstudios7144]

I discovered a similar trick to the king's magic square by taking an x-Sudoku and adding 9 * (n-1) from a 3x3 magic square to each cell in the corresponding region. It works because Sudoku grids are Latin squares and Latin squares are just magic squares with repeating numbers so just like your example it's taking another pattern with consistent sums and adding them together to make each number unique. You can use a similar technique to iterate magic squares creating any square of a length of power 3 (or any length multiplied by another) and it even works for magic cubes, I've checked up to length 125 by iterating a 5x5x5 twice. This video got me thinking you could construct a 4x4 latin square using playing cards and add 0, 4, 8 or 12 to each suit to create a magic square. It works.

[@ozaman-buzaman9300]

Thank you a lot professor Burkard, you are truly enlightening my life

[@NoobsDeSroobs]

This might be the most mindblowing piece of math I have ever seen. I had problems focusing on the rest of the video because my mind was reeling from the extreme and simplistic beauty of this structure!

[@MisterMajister]

One of your finest videos in my opinion, I really enjoyed it!

[@Mathologer]

Something different. Glad you liked it :)

[@SaturnCanuck]

Thanks again for anther great video. As I said i watch these on a nice Sunday afternoon to relax. :)

[@mlmimichaellucasmontereyin6765]

Bravissimo! Thanks again guys. I love the way that your exploration of truly basic fundamentals of geometric-numeric logic inspire new ideas about efficient coding, data structures, etc. Cheers etc. ~ M

[@TimothyHilgenberg]

Another great video to share with my DP HL students. Thank you!

[@eligilboa1968]

Great, as always!

[@omrizemer6323]

I was shaking my head with disbelief half the time while watching this video. Amazing

[@ZER0--]

Brilliant. I will never forget how to make magic squares. Love it. I don't know if it will come in handy but I love it.

[@thek3nger]

I followed a lot of math youtuber for years. Mathologer is really the only one that consistently blows my mind.

[@Mathologer]

Mission accomplished :)

[@WildStar2002]

Fantastic video - loved it! 😍 I learned a method of constructing odd order magic squares when I was in Jr High School. It was much later that I became intrigued with even order magic squares. I finally managed to crack that by dividing the problem into even-odd (2, 6, 10, 14, etc) and even-even (4, 8, 12, 16, etc) cases with a different technique for each.

[@sergniko]

This was amazing!

[@cybersandoval]

visual thinker to the point of mathematical difficulties, so these proofs scratch an elusive itch, so satisfying to watch those shapes fit

[@garybartnik1509]

Lovely video on the magic square by a gentleman who is NEVER SQUARE!!! Gary in dreamland. Have a nice dream!!🙂☁️☁️☁️⛅💫🌟🌟🌟🌟🌟👉☁️⏰☁️👈

[@davidalbrecht9117]

Great video. I really loved learning about Bachet's algorithm and geomagic squares. I was also reminded of orthogonal latin squares when you described Bachlet's algorithm.

[@Mathologer]

I was actually thinking of mentioning orthogonal Latin squares but in the end decided against it :)

[@guest_informant]

I don't know if it's going to come up here but I once spent some time looking at 4x4 Panmagic Squares. There are the usual rows, columns, and diagonals, but, for instance there are also all 2x2 sub-squares many more sub-patterns.

[@Mathologer]

You'll probably enjoy this one www.futilitycloset.com

[@addyraptor3675]

Gonna be another banger!

[@alokaggarwal6859]

The diagonal construction of magic squares and the geo magic squares were both superbly presented... Really interesting!

[@Mathologer]

Thank you very much, glad you liked it :)

[@n3cr0he11]

You here use some magic to put this video together so nicely! 😍

[@agranero6]

Ok. Im am a huge fan of k-dramas. And now you gave me a double reason to watch this one.

[@Mathologer]

Maybe also watch Melancholia. That one has a lot of nice math(s), too :)

[@agranero6]

@@Mathologer Thanks for the tip.

[@gregoryzavoritniy3089]

Amazing! Thank you!

[@archivist17]

Another very enjoyable video to learn from!

[@neokart2660]

My fav YT Channel. Amazing Video.

[@davicorosello1588]

Magic, as always! 👍🏼👌🏼👏🏼

[@user-xe4it5qo5y]

I never expected I could see a Korean drama in your channel. :-)

[@tom7]

Exceptional storytelling!

[@robertingliskennedy]

outstanding, thank you

[@WonSikShim]

여기서 한국 드라마를 보게 될 줄은 꿈에도 몰랐네요. Never expected to see K-drama in this channel!!

[@Mathologer]

There are a couple of other K-dramas that would be worth covering mathswise. In particular, Melancholia has got some good stuff :) en.wikipedia.org/wiki/Melancholia_(TV_series)

[@four-wingedpaperplanes6829]

I think a part 2 would be great. Geomagic squares. Self tiling, where all of the pieces combine to make larger versions of a single pieces and rearrange the pieces and get any of the other pieces. And....... Geomagic squares that are fractal. With any row combining to make the target shape but also all of the pieces combning to make the same shape but bigger.

[@Mathologer]

Yes, a lot more variations are possible. Maybe have a look at Lee Sallows's book first, or his online gallery of geomagic squares (link in the description)

[@four-wingedpaperplanes6829]

@@Mathologer The book is already on my list to get. The online gallery is amazing

[@ZedaZ80]

*edit:* this was such a cool video For an n-by-n square, the sum is n(n²+1)/2 The entire square is 1+2+...+n*n = n²(n²+1)/2, then divide that up into n "slices."

[@Mathologer]

That's it :)

[@cameronmyron5776]

What is interesting is that you can also turn any magic square into a new one by adding a non-zero integer constant to every square (the summations will change by the side length times the non-zero integer constant). Additionally there is probably some way to generate a new magic square by taking the modulus of every square (need to be careful about creating repeating numbers with certain values for the modulus. Edit: This actually might not be possible. I don’t have an example that it would work without causing a duplicate value).

[@Mathologer]

Yep. There are a couple of other transformations that turn magic squares into new magic squares. Have a look here for a summary: en.wikipedia.org/wiki/Magic_square#Transformations_that_preserve_the_magic_property

[@cameronmyron5776]

@@Mathologer Since I made the comment I was investigating the group structure of flipping the square across the different axes and until I saw the wiki article you provided I completely missed that the group was isomorphic to D8 and could be simplified from 4 operations (a flip across the 4 different axes) to 2 (90 degree turn clockwise and a flip across one of the axes). Thank you for sharing the wiki article.

[@CalvinsWorldNews]

I saw this done as a trick by a teacher, who generated magic squares to a set numbers on demand, in reality they were just doing some maths tricks in their head. Very impressive today but as a child it was like genuine sorcery.

[@VaradMahashabde]

Homeworks : 1) Considering a general nxn square, it is simplest to add the main diagonal, whose points stay in that diagonal. It becomes the middlemost row post transformation. Their points are (i,n-i) (1 at (0,0)) and the values are n+(n-1)*i for i from 0 to n-1. Adding, we get n^2 + n(n-1)^2 /2 = (n^3 +n)/2. For a 33x33, we get 17985.

[@quantumgaming9180]

I got 17688 ;-;

[@jursamaj]

The way I went: there are 33*33=1089 tiles on the board. The sum of all tiles 1 to 1089 is the 1089th triangular number: 1089*1090/2=593,505. Divide *that* by the 33 tiles in any row, and you get 17,985.

[@Nikolas_Davis]

@@jursamaj That's how I did it also. Very simple and straightforward 🙂

[@wkelly4963]

Very good you explained it in a way other people can understand. 👍

[@EspritBerlin]

Vielen Dank für das tolle Video!

[@nemesisurvivorleon]

I love how Taoism and the brilliant mathematical patterns therein are just casually a core part of Korean culture. South Korea's flag is literally the Taijitu and Ba Gua. It's great.

[@UncoveredTruths]

awesome video :) thank you Burkard!

[@darrennew8211]

How delightful! I'm gonna 3D print one of these for sure.

[@bob-ym3gk]

loshu is never old!(just inscribed on a turtle shell🐢).Love this channel!

[@ProfessorBeautiful]

Like many others in Mathologer-land, this video has helped me with some elementary school students I tutor. They need exercise in simple arithmetic, and need even more a window into how exciting and powerful math can be. As for me, I am now 4 episodes into Tree With Deep Roots. I got goosebumps watching the king solve the 33x33 square. Now I'm reading all this 15th century Korean political history. What a gas!

[@fedimser]

Great video!

[@howwitty]

Excellent!

[@saxbend]

Lesson learnt. There's always more to magic squares. Was not expecting that!

[@withmuchrespect]

Fascinating!

[@christopherellis2663]

I was looking at MSs a month ago. This threw new aspects into the mix. 🙏I like the music 🎶

[@KillianDefaoite]

Very interesting topic!!

[@moin85]

Q: What’s the only thing better than a Mathologer video? A: Another Mathologer video

[@wmafyouni]

Marvelous content! The hidden theme of balancing the numbers around the mean itched my mind, but once I saw the solution I was in awe of the elegance of Bachet's algorithm. Can't wait to implement it in python.

[@Mathologer]

Definitely let me know when you are done :)

[@grandomart]

or try magic(n) in matlab and you are done :)

[@wmafyouni]

​@@grandomart As awesome as it is that someone decided to include a base function for magic squares in MATLAB, it is not open-source

[@wmafyouni]

@@Mathologer I added it in a reply, but it didn't post. Is it because I included a link? The URL leads to a github repo that contains the source code. Not sure if theres a comment filter for posts with links.

[@torbjrnwikestad28]

I obsessed a while ago about completing a program for random search for magic squares. I am not naturally inclined to think in terms of math, so the solution, albeit working, was highly inefficient. I were fascinated by the huge possibility space of the combinatorics behind the problem. I think magic squares of size 7 and beyond has been statistically explored, but not fully mapped, because number of solutions (but even more so, the number of non-magic arrangements) so quickly explodes into inexhaustible spaces. Seeing this video, I appreciate more math as a tool to express the logical patterns behind the magic squares. I think there must be mathematical expressions still to be discoved that generalises the rules and constraints for all the possible solutions of higher order magic squares.

[@rserserserse]

Wow, really beautiful!

[@pesilaratnayake162]

Great video. Magic squares are classic puzzles. The insights I help my students understand for 3x3 magic squares is the sum is triple the central number, and all lines through the centre are arithmetic sequences. This can be seen in the general solution to the 3x3 magic square (with a, b and c), which we derive if the student is up for it. This makes solving 3x3 easy with very little information required - I think any 3 values can be used except if they are one vertex and the opposite two edges, or all three values in a line through the centre (assuming any solutions exist). In those cases, the problem is underdetermined.

[@mohammadburhanmanzoor3806]

Pretty magical!!

[@alexpotts6520]

In case you're wondering, the dots on his shirt are the digits of pi

[@miguelarribas9990]

"Since this will probably be my only ever Mathologer video on magic squares" ... I am already waiting for the next video on magic squares (or maybe magic cubes?) 🤩🤣

[@frankharr9466]

I've been testing my understadning of the mousatche method using the 33x33 square. It's been a journey so far. Drat you for making me do something interesting! ;)

[@yinq5384]

Great video as always! 8:24 The sum of all tiles from an order-n magic square is S = 1+2+...+n^2 = n^2(n^2+1)/2. Thus the magic number should be S/n = n(n^2+1)/2. It's 17985 when n=33. 18:50 Extend the square to the whole plane by translating horizontally and vertically (similar to the flat torus). Start from the middle tile in the top row, go towards top-right diagonally 4 times, then go down 1 tile. Repeat. P.S: There are 5 different starting places of tile 1 for this method to work (to make sure that 11 through 15 are the five numbers on the "/" diagonal). Actually, it's better to start from tile 11 - we just need it to be on the "/" diagonal. BTW, are there any sum-and-product double magic squares? I vaguely remember having read about it before.

[@dexter9313]

Mind=blown, thank you !

[@VikasKumar_iitb]

Just mind blowing

[@Pedritox0953]

The geometrical videos are awesome

[@gackerman99]

Man to see my all-time favorite obscure K-drama come up in a Mathologer video apropos of nothing is going to mess with my head for a while.

[@Mathologer]

I liked the drama but in terms of historical k dramas not among my top 10. I really hated the gratuitous killing of two of the three main characters at the end of the drama :(

[@gackerman99]

I thought the lead tension was done (come on... TAM-AH!!! got you and you know it did!) well and most of all I liked the way the politics were handled. The "bad guys" were well-motivated. There was some well-handled anachronistic philosophy. You don't see that often. And it wouldn't be a proper kdrama if they didn't completely bungle the ending!

[@beanhwak]

Great video

[@ominollo]

Beautiful 😊

[@SuperDreamliner787]

I was showing the first part with the 3x3 grid to my 5th graders yesterday to teach them a technique to create their own 3x3 magic square. Their mind was blown. Thanks! Greetings from Leipzig 😄

[@Mathologer]

That's great :)

[@MuffinsAPlenty]

Interesting! I was actually informed of the Benjamin Franklin magic square (and magic circle) just a day before this video released! Now I'm thinking about things like geometric magic circles.

[@NaHBrO733]

The magic square proof is brilliant! To generalize it, i turned the tiles' numbers into coordinates for a n*n square, T=x+(y-1)*n, 1(1,1), 2->(2,1) etc. arrange the tiles into the big tilted square as the video shows, for every tile T, the only tiles that share a common x or y coordinate are the ones that share the same diagonal with T Thus, every tile on the same horizontal/vertical with T must have different x and y coordinate (that is the first part) Now we define horizontal and vertical distance, which is the number of horizontal and vertical steps required to move a tile to another square (empty or another tile) As the video says, when creating the magic square, all tiles outside moves exactly n steps to it's destination, which gives us a distance (horizontal or vertical) of n However, as there are only n squares on a diagonal, the maximum (horizontal or vertical) distance between T and any tiles that share the same x or y coordinate

[@eliyasne9695]

I have a different perspective on "the king's method". When I went about proving the method, I looked at the form the columbs take when we unwind the magic square back to the lunch box formation. Under that perspective each columb corresponds to two diagonals with a combined leangth equal to that of the columb. Than the key to proving the method is to show that when shifting from a columb to its' adjacent, the sum over one of the corresponding diagonals increase by exactly as much as the sum over the other will decrease.

[@Mathologer]

Nice :)

[@eliyasne9695]

@@gregoryford2532 Sorry, I'm not a native English speaker...

[@78Mathius]

Great, now I have so many questions I want answered. Shapes: All shapes must be constructed from an integer number of squares connecting to each other across full edges. N=side length C=the magic number. 1. For what N is there a constant shape that is a square? 2. Is there an N with a set of shapes that only add to a square? 3. If a square can be built, it must have a C with a square root equal to or larger than the triangular number of N. Is there an N where all squares are possible once the minimum square size is reached? 4. Earliest N with a set of consecutive integers that can build a square? 5. So many more.

[@john-ic5pz]

mind blower: draw a line connecting 1, 2, 3 and 7, 8, 9. connecting 4, 5, 6 forms an axis. blew my mind at least