This completely changed the way I see numbers | Modular Arithmetic Visually Explained

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  • čas přidán 12. 06. 2024
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Komentáře • 1,6K

  • @zachstar
    @zachstar  Před 4 lety +893

    2:50 should be "For any composite number x one of its prime factors must be less than OR EQUAL TO its own square root." (the 'or equal to' part only would apply to primes squared but still needed to be included). I was so focused on my specific example and wasn't thinking lol. Thanks to those who caught it and hope you guys enjoy the video!

    • @ratamacue0320
      @ratamacue0320 Před 4 lety +40

      Also "its" (as you have here), not "it's" (as in the video).

    • @ratamacue0320
      @ratamacue0320 Před 4 lety

      5:18 should that be 9 modulo 7 = 2?

    • @chessandmathguy
      @chessandmathguy Před 4 lety +4

      @@ratamacue0320 the way it's phrased in the video is perfectly fine

    • @zachstar
      @zachstar  Před 4 lety +18

      @ratamacue0 both will work in regards to the 9 = 2 (mod7) or 9 (mod7) = 2

    • @ratamacue0320
      @ratamacue0320 Před 4 lety

      @@zachstar I guess you're using it as a descriptor, not an operator.

  • @Ratzfourtyfour
    @Ratzfourtyfour Před 4 lety +4002

    This completely changed the way I don't understand numbers.

    • @dogwithwigwamz.7320
      @dogwithwigwamz.7320 Před 4 lety +95

      I agree. Why make understanding easy when you can make it hard ?

    • @dogwithwigwamz.7320
      @dogwithwigwamz.7320 Před 4 lety +19

      YT : "Euclid`s Algorithm." As of today ( October the 25th, 2019 ) click on the first video in the list - by "Learn Math Tutorials;" Its not my work. If it had been it would be called "Learn Maths Tutorials."
      To my mind it offers a far simpler explanation of the introductions to Modular Arithmetic.

    • @charlesquarra5050
      @charlesquarra5050 Před 4 lety +47

      this post has 365 likes, which equals the numbers of trips earth does around itself for every trip it does around the sun, while the moon does 1/28 trips around itself for every trip it does around the earth, since 28 * 13 = 280 + 28 * 3 = 280 + 30 * 3 - 2 * 3 = 280 + 90 - 6 = 364. Which means that the moon takes 13 trips around the earth plus one trip of the earth around itself for the earth to make a trip around the sun
      Hope that clears things up

    • @lungflogger9
      @lungflogger9 Před 4 lety +11

      agree, this makes NO sense. he may be factually correct but so what.....?

    • @greatkingkay7954
      @greatkingkay7954 Před 4 lety +5

      @@hassanakhtar7874 yea I saw perfect circles and rays coming from the center.

  • @canadiannuclearman
    @canadiannuclearman Před 4 lety +1780

    I was a machine designer for a few years number theory is geat for gear train design. Thanks for the video.
    I designed a concentric speed reducer once. The ratio was 6.0025 to 1.
    My boss said why not 6 to 1? I said because the square root of 6 is an irrational number. He asked why and i said because the number of teeth in the 1st gear is 20 the second is 49 thats on the same shaft as the 3rd gear that has 20 that drives the 4th gear with 49 teeth. Fun and interesting.
    Prime numbers with gears are cool too.
    If you have 2 gears with number of teeth 12 and 60
    This means every tooth in the gear with 12 will match every 5th tooth and only that tooth per revelotion and not engage any others this increases ware on the teeth. But in the above 49 is divisable by 9 and 20 divisable by 2 and 5. There is no common prime between 20 and 49. Because 20=2×2×5 & 49=7×7. This means that each tooth of one gear will eventualy mesh with every tooth of the second gear. Therefore spreading ware over all the grear teeth.

    • @zachstar
      @zachstar  Před 4 lety +353

      I definitely learned something from this. Never thought about number theory being applicable to something like that but makes perfect sense. Thanks for sharing!

    • @maxwellali
      @maxwellali Před 4 lety +110

      Wow you fooking genius

    • @johnyepthomi892
      @johnyepthomi892 Před 4 lety +38

      Wow.. mind blown.

    • @edstirling
      @edstirling Před 4 lety +78

      this is the most interesting thing i've heard in a while.

    • @ntwede
      @ntwede Před 4 lety +16

      How does gear tooth wear depend on which tooth of the other gear it meshes with? I'd say it really only depends on how many times it contacts the other gear which depends only on the number of teeth in the gear (For a given number of rotations)

  • @captainsnake8515
    @captainsnake8515 Před 3 lety +169

    Tip: if you’re a high schooler interested in competition math, modular arithmetic is one of *the* most important topics to study, since normal classes don’t tend to teach it much, but math competitions love modular arithmetic questions because they make for really interesting problems.

    • @l1mbo69
      @l1mbo69 Před 2 lety +3

      anyone interested would already know this

    • @danpalu2308
      @danpalu2308 Před 2 lety +58

      @@l1mbo69 what an arrogant comment. Surely someone who just got introduced to the concept of competition math mighy not yet now that.
      Heck, some may not even have known of competitive math until they read Captainsnake's post. And maybe Captainsnake's post thus inspired someone to take competitive math up, or maybe just inspired them to spend a little more time on learning math in the first place.
      So Captainsnake's post added value. But your post added only vitriol.

    • @l1mbo69
      @l1mbo69 Před 2 lety +1

      @@danpalu2308 first of all in countries with a screening round of sorts (US, China and India all come in this category) modular math really only becomes important after the first stage. So the comment holds true only for those that have already qualified or are confident will qualify the first stage. Just tautologically these people wouldn't be complete beginners.
      And even otherwise, i would expect someone interested in competition math to atleast go through the list of common topics, yk. If they haven't yet they will in the future irrespective of this comment. Otherwise they aren't really serious to begin with
      I don't really see how this could be taken as inspirational by anyone, but anyway my comment wasn't really supposed to be vitriolic but rather just casual, so sorry if it came off as so

    • @l1mbo69
      @l1mbo69 Před 2 lety +1

      @@danpalu2308 oh and i just remembered, this is not even true for all countries. Iirc, UK devotes a decent amount of time in covering modular arithmetic. Sounds pretty US centric to me

    • @peamutbubber
      @peamutbubber Před rokem +7

      @@l1mbo69 not everyone goes to a good school or has access to good resources

  • @bunberrier
    @bunberrier Před 4 lety +609

    I cant find the wheel thing on my calculator.

    • @XxBobTheGlitcherxX
      @XxBobTheGlitcherxX Před 4 lety +9

      its the %

    • @noobita4983
      @noobita4983 Před 4 lety +11

      Mod operator isn't available in most of the calculators

    • @whatelseison8970
      @whatelseison8970 Před 4 lety +13

      @@noobita4983 It's possible to make the mod function from functions all scientific calculators do have. Namely arctan(tan(x)). They are both rising sawtooth functions. If you have a computer, and internet you have access to desmos. Google it. Use it. You won't regret it.
      It sounds like a fun puzzle. I wish I could be more help but my god... I'm just up way too late at this point. Good luck.

    • @whatelseison8970
      @whatelseison8970 Před 4 lety +9

      @@noobita4983 x mod a = (a/pi)*arccot(cot(pi*x/a)). It can also be done the way I mentioned above but it's more work. I'm not going to type it out. See my work here: www.desmos.com/calculator/1btmjt4fdi

    • @AlainNaigeon
      @AlainNaigeon Před 3 lety +1

      Thus you're the kind of guy who could NOT have written your calculator software.

  • @dbaker280
    @dbaker280 Před 4 lety +769

    Holy shit. In 20 minutes you covered almost 70% of the topics on the syllabus of my number theory class.

    • @alexv5581
      @alexv5581 Před 4 lety +43

      You must go to a shitty school.

    • @CamMackay96
      @CamMackay96 Před 4 lety +36

      Do you mean lecture? There's no way a whole semester course is covered by this video, this was about one lectures worth of material from my undergrad Number Theory course....

    • @CamMackay96
      @CamMackay96 Před 4 lety +15

      @No Name can't say I've studied fractals so idk what you want me to tell you, I'm perfectly willing to admit I have specialty areas, Number Theory being one of them. Since you brought it up, why don't you share with the class?

    • @CamMackay96
      @CamMackay96 Před 4 lety +25

      @No Name what does any of that have to do with fractals and primes...?

    • @That_One_Guy...
      @That_One_Guy... Před 4 lety +1

      @@alexv5581 This is taught in College

  • @DownWithBureaucracy
    @DownWithBureaucracy Před 3 lety +82

    This video game me flashbacks to math class. Started out understanding everything, feeling good about life, and then suddenly I'm lost. "So naturally we can see that..." no. No I cannot see

  • @wojocolebuilds
    @wojocolebuilds Před 4 lety +57

    The 12 spoke wheel reminds me of music theory and the circle of fifths, a model that visually represents harmony and dissonance between different tones of sound(music notes). The circle of fifths, comprised of the 12 notes of the chromatic scale, visualizes intervals that would fully revolve a musician around the chromatic scale. These intervals, despite whatever root note you start off with, are constant in all musical harmony and dissonance.

    • @uaswitch
      @uaswitch Před 2 lety +11

      it isn't incidental - if you work with addition on the entire spokes, then adding 1 repeatedly will cycle through every spoke exactly once with no repeats. The same thing will happen with adding 5 repeatedly, adding 7 repeatedly, or adding 11 repeatedly. If you view label the spokes as A, A#, ... through G#, then the adding 7 repeatedly is the circle of fifths, and the reason cycling through the circle of fifths involves every note exactly once is precisely due to the fact that 7 and 12 have no common factors. I use this example in my modern algebra class when we discuss cyclic groups.

  • @Nomenius1
    @Nomenius1 Před 4 lety +645

    This would be incredible if I could remember it all the time

    • @missionpupa
      @missionpupa Před 4 lety +50

      Math is not about rote learning. Its about understanding. If you understand it, you never have to remember anything.

    • @ajs5753
      @ajs5753 Před 4 lety +5

      Feralz primes.

    • @shanaadams4456
      @shanaadams4456 Před 4 lety +1

      Right? lol

    • @MMABeijing
      @MMABeijing Před 4 lety +12

      first make sure you actually go over the content slowly and let your brains digest the finer details

    • @hassanakhtar7874
      @hassanakhtar7874 Před 4 lety +5

      EDIT: It's been 2 years and I've reflected on myself. What I said was absolutely negative and insulting for no reason. You can belittle me back or forgive me, I'm really sorry.

  • @insertname252
    @insertname252 Před 4 lety +815

    “With that background you should now be okay with this theorem”
    Me:

    • @funkahontas
      @funkahontas Před 4 lety +36

      My calc II teacher in a nutshell lmao

    • @seanhatton4013
      @seanhatton4013 Před 4 lety +1

      🤣🤣🤣

    • @tinnnyz
      @tinnnyz Před 4 lety +1

      😂😂😂

    • @lekhapratap1652
      @lekhapratap1652 Před 4 lety +6

      My little bro asked me to explain to him tonight.
      Me:
      “I went to fucking music school. I don’t know number theory, kid.”
      I’m trying to understand but “excuse me. That’s like that asylum demon boss at the start of dark souls.”

    • @waynethomas1726
      @waynethomas1726 Před 4 lety +2

      @@funkahontas I learned enough Algebra to be good with Trig but the more advanced Algebra, remembering the Quadratic equation...sucked! Of course it turned out that nobody wanted me to use my calculator to do anything. the computer could do it far more accurately by drawing the geometry. And then the classic "you don't use it you loose it" came into play. Only a few years out of the design field and I can't do trig either. This made my brain hurt.

  • @michaelfruge421
    @michaelfruge421 Před 4 lety +435

    A professor once made us write out our work on graph paper. One character per cell. If the character drifted out of the cell, the grade was a zero. He specified every single minute detail. It was quite controlling.
    However. He didn’t specify what number system. I wrote the entire problem, and solution in Roman numerals because he didn’t specify Arabic numerals.
    He returned my paper with:
    “Touché 100”

    • @Jacob-ye7gu
      @Jacob-ye7gu Před 4 lety +196

      He should have just given you a "C" to mess with you

    • @m3xikanolokoruiz
      @m3xikanolokoruiz Před 4 lety +157

      "and then the whole room gave me a standing ovation, and the hottest girl in class asked me to marry her"

    • @CZghost
      @CZghost Před 4 lety +9

      Definitely a mad lad :D

    • @jazz4dayz543
      @jazz4dayz543 Před 4 lety +32

      @@m3xikanolokoruiz Bruh, I've had professors as he describes myself. It's not such an unbelievable story..

    • @1oo1540
      @1oo1540 Před 4 lety +7

      m3xikanolokoruiz you tell all the best stories, I hear you’re super fun at parties

  • @halasimov1362
    @halasimov1362 Před 3 lety +58

    Reminds me of the harmony of 2 notes. Even when the 2 notes are moved too different octaves they still multiply and create a similar freq that would seem to fall in the same spoke if you will.

    • @nell__byte
      @nell__byte Před 2 lety +3

      That's what I was reminded of as well, though I was specifically reminded of the circle of fifths.

    • @jamessloven2204
      @jamessloven2204 Před 2 lety

      Hi

  • @_Hound_
    @_Hound_ Před 4 lety +303

    Ten seconds in, and I realized that I'm on the wrong video. I'll see myself out.

  • @thatnativeking1333
    @thatnativeking1333 Před 4 lety +254

    I still see numbers with my eyes.

    • @anilkumarsharma1205
      @anilkumarsharma1205 Před 4 lety +2

      when number become experience then we sensing the numbers not merely see them like speed of light and intensity of laser light or power of hydrocarbons or hydroelectricity dam or hydraulic pressure machine power and many degree of time and randomness and temperature etc

    • @prim16
      @prim16 Před 4 lety +9

      @@anilkumarsharma1205 beautiful job detecting danny's sarcasm, i cried

    • @anilkumarsharma1205
      @anilkumarsharma1205 Před 4 lety

      number are for information we see the numbers with eyes, hands, touch, sound or any other means so we know mann ki aankhon sey dekh saktey hain

    • @whatelseison8970
      @whatelseison8970 Před 4 lety +2

      I see colors too sometimes

    • @neonblack211
      @neonblack211 Před 4 lety +1

      Great comment

  • @shanaadams4456
    @shanaadams4456 Před 4 lety +13

    I put off learning modular arithmetic for so long because it looked dauntingly difficult. I can't believe it's this easy! Thanks for making stats much easier for me :)

  • @user-tn3fo3pj2x
    @user-tn3fo3pj2x Před 4 lety +59

    holy holy holy .... they say a genius creates good math, but need another genius who can explain it well!

    • @louiseevans5752
      @louiseevans5752 Před 4 lety +4

      & need another genius to understand it !!!

    • @Verinenkorppi
      @Verinenkorppi Před 4 lety +2

      Just another day of creating math at the math factory

    • @HighestRank
      @HighestRank Před 4 lety

      Xiao Zhang
      czcams.com/video/X6wnksrEbhw/video.html

  • @SM-qk7jv
    @SM-qk7jv Před 4 lety +99

    MajorPrep still making next-level videos. Keep up the great work.

    • @wallonice
      @wallonice Před 4 lety +3

      @@yisu575 His level is determined by a wheel with 23 sections, starting with 1. He got number 24

    • @1.4142
      @1.4142 Před 2 lety +1

      Who's majorprep?

  • @SeeThat92
    @SeeThat92 Před 4 lety +48

    Your wheel numbers explanation was brilliant

  • @basspuff514
    @basspuff514 Před 3 lety +9

    This is so fascinating. I love when seemingly really hard problems have clever solutions like this.

  • @siobhanbartz2688
    @siobhanbartz2688 Před 4 lety +11

    This video was super amazing. I now know that I am interested in number theory. You explain things in a way that all age ranges could understand. Honesty, I love your videos! Keep up the outstanding work!

  • @lewismassie
    @lewismassie Před 4 lety +230

    So it's called the digital root. I've been looking for that term for about 10 years

    • @gauravcheema
      @gauravcheema Před 4 lety +27

      And the number of additions required to get to digital root is called the additive persistence of that number.

    • @lordx4641
      @lordx4641 Před 4 lety +8

      @@gauravcheema well isn't this called vedic mathematics in ancient India? I mean I read this in vedic maths books

    • @ChrisTian-uw9tq
      @ChrisTian-uw9tq Před 4 lety +2

      Woah 10 years is some time! I am clocking up 7 years :) Vedic Square the start point ;) Got any outputs online somewhere to inspire? What do you feel it is leading you to? Do you have some education behind you or is it self learned?

    • @milanstevic8424
      @milanstevic8424 Před 4 lety +2

      @@lordx4641 also numerology -- but yep, digital root

    • @lordx4641
      @lordx4641 Před 4 lety +2

      @@milanstevic8424 yes sir I read vedic maths nd Vedanta so that gives me a very deep rooted understanding of mathematics and it's structure or let's say patterns

  • @georgepaul6240
    @georgepaul6240 Před 4 lety +408

    This completely changed the way I see numbers

  • @HA7DN
    @HA7DN Před 4 lety +16

    We've learnt this in high school, but using this chart more of us would understand this.

  • @grantyentis5507
    @grantyentis5507 Před 4 lety +57

    Now I remember why I hated math in junior high and high school. They always go too damn fast without giving a firm foundation to what's going on. It's like it starts making sense then they pull this twist that breaks the rule of what I thought I just learned. I have a headache now.....I'm going to eat cereal.

  • @rogerlow9107
    @rogerlow9107 Před 4 lety +57

    Maths was never fun like this
    Thank you for wonderful videos

    • @vojtechstrnad1
      @vojtechstrnad1 Před 4 lety +6

      Well you obviously don't watch 3Blue1Brown.

    • @cyanprint001
      @cyanprint001 Před 4 lety +2

      @@vojtechstrnad1 All hail Grant.

    • @gflow8357
      @gflow8357 Před 4 lety +1

      It has always been fun. You just have to look in yourself if your instructor doesn't know what is going on.

  • @OG-ds4iy
    @OG-ds4iy Před 4 lety +92

    Uhm...I lost u at “hello”, but still made me feel smart 😂😂

  • @BKNeifert
    @BKNeifert Před 5 měsíci +2

    I always forget he's an engineer. He's very gifted, to have such humanity and also such a grasp of mathematics, too. That's a rare combination of skills.

  • @bobminion3438
    @bobminion3438 Před 4 lety +13

    Hi @Zachary while watching your video i converted whole calendar into single 7 spoke wheel arrangement. Now i can easily predict dates, on which day it falls.( _Although there exist an algorithm but this visualization helped me_ )
    Thanks for such intuitive videos 🙂

  • @sircyborg
    @sircyborg Před 4 lety +4

    This is actually insane. I don't have a high education in math, but my hobbies makes me use it on many occasions. Many times, I don't know any formulae, so I'll have to make my own (inefficient, but with accurate results) formula. Those videos remind me of those hours figuring out how to math. The person who came up with this particular trick must really have put in some work. Impressive!

  • @MichaelPohoreski
    @MichaelPohoreski Před 2 lety +5

    @3:56 An easy way to tell if an integer > 10 is divisible by 7 is to subtract twice the last digit from the remaining digits and check if the result is divisible by 7. Repeat if the result is > 10.
    For 119, rewrite as 11 - 2*9 = 11 - 18 = -7 which is divisible by 7.

  • @macroxela
    @macroxela Před 4 lety +2

    I never quite understood Fermat's Little Theorem but with your visualization it all makes sense now. Thanks for explaining it in such an elegant way!

  • @masontdoyle
    @masontdoyle Před 4 lety +2

    An engineer has become a number theorist. What a beautiful timeline we live in!
    In all seriousness though, when I was learning modular arithmetic for my Number Theory class there was no video of this quality on CZcams to learn it. Thank you for this awesome video!

  • @Ollivie13
    @Ollivie13 Před 4 lety +15

    Tbh I still have difficulty taking all this in, but in I'm amazed that you point out things like this.

    • @CamMackay96
      @CamMackay96 Před 4 lety

      This is quite basic level undergraduate maths my dude! Get reading, your mind will be blown repeatedly!

  • @fareedabifarraj483
    @fareedabifarraj483 Před 4 lety +3

    Great great great video, I watched it from begining to end and enjoyed every single minute of it.
    Thank you so much for your hard work, although I learned about all these things before but putting them all together, the wheel form, and putting the mathematical theorem behind it...
    I mean simply WOW!
    Mathematics is the beauty of life😍

  • @RiDankulous
    @RiDankulous Před 2 lety

    I come across thousands of videos on CZcams that really are mundane to me, and then one that is completely genius and this is one of the great ones. It's worth sifting through the others!

  • @Thrlta
    @Thrlta Před rokem +1

    Such an epic way to plug your sponsor btw, actually showing how what you teach on your channel can be a useful method to use on Brilliant's test, and that these are the sorts of topics covered by Brilliant.

  • @KipIngram
    @KipIngram Před 4 lety +11

    Ok, this taught me some things. Deepest thanks, Zach! I consider myself "good with numbers," but there was some fresh material for me here. And super well explained, too. :-)

  • @TheKradok
    @TheKradok Před 4 lety +7

    2:08 was really confusing for me. I understood it as a! is not divisible by any number i where {i ∈ Z | i > a}. Completely missed that it's actually {i ∈ P | i > a}. After listening to it a bunch of times 2:36 made me realize what was going on.

  • @Albert-fe8jx
    @Albert-fe8jx Před 2 lety +1

    Enjoyed watching. I appreciated the effort put into designing and animating the visualizations.

  • @cjcote3490
    @cjcote3490 Před 4 lety +4

    well, this has officially blown my mind.

  • @L0j1k
    @L0j1k Před 4 lety +56

    Haha man... Imagine cooking up some teriyaki burgers, smoking a little dope, and then discovering a new video of mathbro talking about NUMBER THEORY ARE YOU KIDDING ME. Literally the best Sunday I've had in months.

  • @spandansaha5663
    @spandansaha5663 Před 4 lety +121

    After watching this video
    *My brain has left the chat*

  • @area51xi
    @area51xi Před rokem

    This is one of the best videos EVER made on CZcams. Possibly life changing.

  • @cvm7549
    @cvm7549 Před 3 lety

    Fascinating and perfectly explained with visual effects, thank you!

  • @dogmeat7486
    @dogmeat7486 Před 4 lety +11

    I'd give every last cent i have to be able to remember this when i need it.

  • @guillev5420
    @guillev5420 Před 4 lety +10

    When you already know number theory but still get mind blown

  • @a-levelmathstutorials9175

    you have earned yourself a subscription my friend, great way to visualise modular arithmetic

  • @ldonnell4437
    @ldonnell4437 Před 3 lety +1

    I'm taking a semester of Number Theory this year and this video has been a life saver!!

  • @x78340
    @x78340 Před 4 lety +8

    Cryptography is sooo interesting. Thank you for talking about it!

  • @blacksky7091
    @blacksky7091 Před 4 lety +66

    3:35 it should be less or equal right? example 4 = 2 * 2 sqrt(4) =2

    • @zachstar
      @zachstar  Před 4 lety +24

      Yep! My bad for forgetting perfect squares lol

    • @blacksky7091
      @blacksky7091 Před 4 lety +11

      @@zachstar squares of prime numbers

    • @mohamedboulaich5450
      @mohamedboulaich5450 Před 4 lety

      But 2 is less or equal to 2

    • @mohamedboulaich5450
      @mohamedboulaich5450 Před 4 lety

      @No Name i don't understand u
      I said even for perfect squares the proposition is right

  • @funahead5426
    @funahead5426 Před 4 lety +1

    simplicity in your explanation is the key factor that attracts each and every people that watches your video for the first time also subscribe to your channel.

  • @Lisa-pe6dl
    @Lisa-pe6dl Před 3 lety

    Thank you😊, I will watch it in full detail over the weekend

  • @Xabraxus
    @Xabraxus Před 3 lety +3

    I never liked using the modulo in programming because it seemed like something that could become difficult mathematically, this video helps immensely with abating that fear.

  • @rishi1679
    @rishi1679 Před 4 lety +47

    You enlightened me
    Thanks
    Please make a video on engineering physics

    • @alexv5581
      @alexv5581 Před 4 lety +8

      Or you could do your own research. Its a useless degree option, are you trying to be an engineer or a scientist? Both different disciplines and mindsets. Are you an abstract thinker who likes to think why something happens? Or are you a practical thinker who likes to understand how something works? If you can be honest with yourself than one if these professions is for you. The world needs smart and good scientists and engineers, not some person who holds a degree and claims to be an engineer or scientist.

  • @matyaspoko
    @matyaspoko Před 3 lety +1

    This is probably the most comprehensive explanation of Fermat's little theorem I've ever seen!

  • @gwensimmons_gigi1629
    @gwensimmons_gigi1629 Před 3 lety +1

    Loved this episode; thank you!

  • @ryanrrree1744
    @ryanrrree1744 Před 4 lety +21

    My brain could focus but at the same time couldnt
    I love these kind of videos tho
    Please make more

  • @bigpickles
    @bigpickles Před 4 lety +38

    44 seconds in and I'm confused already.

  • @mkiemkie
    @mkiemkie Před 4 lety +1

    Wow! This is really AMAZING!

  • @homelessrobot
    @homelessrobot Před 3 lety +1

    modular arithmetic is so fascinating, especially in how it relates to machine arithmetic and memory addressing in computers. I guess it kind of makes sense thinking about it as 'wheel math' when you think about how generally useful things gears are in mechanical computation engines. Everything is always wrapping around, and complete circuits of one gear generally leads to some much smaller amount of movement in a larger gear, the evenness, odness, and primeness of the amount of teeth in a particular gear lead to broad reaching consequences in the behavior of the rest of the system.

  • @OwlexMyth
    @OwlexMyth Před 4 lety +4

    You mentioned several times that given X, the relative numbers ended up in "the same section", when the referenced numbers (highlighted) were clearly not in the same sections.

    • @joanagomes1898
      @joanagomes1898 Před 4 lety +2

      I think he means that if you add a number from section x and and a number from section y you always get a number from section z.

  • @zsoltsz2323
    @zsoltsz2323 Před 4 lety +7

    You can also immediately see if 119 is divisible by 3 if the sum of the digits is: 1+1+9=11, not divisible by 3. (On the other hand e.g. 252: 2+5+2=9, divisible by 3.)

  • @manganari8022
    @manganari8022 Před 5 měsíci +2

    at the beginning of this school year i discovered modular arithmetics in the notebook of an older student, the first thing i did with the power i was just given was make an unbreakable code to send messages to my friends, for those interested what i first did was converting text to morse so - and . then changing it to binary 0 and 1, and then attirbute any number wit a rest of a when divided by an integer x to , same for 1 with any number congruent to b mod x, and then the only thing you need is the key looking like this [x,a,b] to crypt or decrypt the message, it was stupid, it was not useful at all, it was not optimized either, But oh my god it was fun

    • @tone618
      @tone618 Před 25 dny +1

      Lmao you discovered the basics of rsa encryption

    • @manganari8022
      @manganari8022 Před 25 dny +1

      thx, thanks to you i'm going to spend my 6 hours left to sleep in order to learn about that and make a better encryption method, then code it in some way, make UI for both encryption and decryption, then, then hmm, what can i actually do with that...

  • @dianedong1062
    @dianedong1062 Před 3 lety

    I appreciate the visual explanations in this video.

  • @sb-hf7tw
    @sb-hf7tw Před 4 lety +3

    I wish I had the same level of thinking as of yours, major prep.
    Excellent excellent excellent work.
    😘😘😘😊👍👌🙏 From INDIA, LOVE. YOU...

    • @sb-hf7tw
      @sb-hf7tw Před 4 lety

      Thanks again major prep😊

  • @Ash-zm1vx
    @Ash-zm1vx Před 4 lety +6

    Ah yes, I remember figuring out that every prime (except 2 or 3) is 1 more/less than multiple of 6, since 3 more/less is multiple of 3, 2 more/less is multiple of 2. Still I was surprised about how that could be applied!

  • @RealLifeKyurem
    @RealLifeKyurem Před 3 lety +2

    Actually, for the example with 119, you can reduce the number of tries to just 1. Just check if it’s divisible by 3. Checking if a number is divisible by 2, 3, and 5 are easy enough. 7 and beyond are quite harder.

  • @alanr4447a
    @alanr4447a Před 3 lety +1

    A minor thing I did with modular math: Given the integers 1 to 9, there are 84 combinations of three numbers picked from those 9. Some years ago I received a computer program where an array of 84 "items" represented all 84 of those combinations. The program would go through a succession of picking one "item", and putting it through the series of "tests", with A, B and C standing for the three numbers represented by the "item". It frequently came up in these "tests" to ask variously if a certain number of the 1 to 9, each called x for its occasion, was anywhere among the three numbers (A, B or C) represented, which the program would do by asking for each, "is A equal to x, or B equal to x, or C equal to x?" I used modular arithmetic to reduce those three questions to a single test question. When the "item" was initially chosen for examination, I would formulate for each of A, B and C (called "y") the value 2*y+15, and multiply the three values for A, B and C together, and call that N. In 2*y+15, 1 to 9 produces 17, 19, 21, 23, 25 , 27, 29, 31, and 33. The nice feature of these 9 consecutive odd numbers is that all 9 contain factors unique to them. Five of them are prime outright. 21 is the only one with a factor of 7, 25 has the only factor of 5, and 33 has the only factor of 11. And while 21 and 33 provide two factors of 3 between them, only 27 has a THIRD factor of 3. Thus, multiplying various of these numbers together cannot "inadvertently" produce one of the other numbers as a factor of it. With this N, then, to test whether any x was among the three numbers, I would just ask the one question, "does N MOD (2*x+15) equal 0?" If yes, then x was among the three numbers represented.

  • @EpicMathTime
    @EpicMathTime Před 4 lety +56

    One of my favorite problems is a "word problem" that sounds simple, but is based in modular arithmetic. Asking people that haven't studied modular arithmetic to solve it is kind of interesting, because they try for a while and then suddenly they have the epiphany that there is a huge gap in their knowledge of arithmetic.
    Here is the problem:
    A group of 50 pirates finds a chest of gold coins. After the coins are distributed evenly among the pirates, they find that there are 6 gold coins remaining. After a heated argument about how the remaining 6 coins should be distributed, two of the pirates are killed. The coins can now be split evenly among the crew.
    What's the smallest number of coins that could have been in the chest?

    • @Ennar
      @Ennar Před 4 lety +4

      Thanks for that problem. Boils down to a linear Diophantine equation.

    • @abhavyakeerti8599
      @abhavyakeerti8599 Před 4 lety +1

      So what's the answer, 336??

    • @Ennar
      @Ennar Před 4 lety +20

      @@abhavyakeerti8599, no, you cannot divide 330 = 336 - 6 evenly among the 50 pirates.
      Let x be the number of gold coins. Then the problem tells you that 50 divides x - 6, and 48 divides x. So, x = 48n and 48n - 6 = 50m. To get relatively prime coefficients, divide by 2 to get 24n - 25m = 3. Since 1 = 25 - 24, then 3 = 3*25 - 3*24, so (-3,-3) is a particular solution of 24n - 25m = 3. Thus, all the solutions are given by (-3 + 25k, -3 + 24k), for some integer k. Since you are looking for the smallest positive n, you want k = 1, so n = 22 and x = 22*48 = 1056.
      If you need more convincing, look at the first 22 multiples of 48:
      {48,96,144,192,240,288,336,384,432,480,528,576,624,672,720,768,816,864,912,960,1008,1056}.
      Now, subtract 6:
      {42,90,138,186,234,282,330,378,426,474,522,570,618,666,714,762,810,858,906,954,1002,1050}.
      Only the last one is divisible by 50, so that one corresponds to the smallest possible number of coins.

    • @abhavyakeerti8599
      @abhavyakeerti8599 Před 4 lety +4

      @@Ennar thank you, I am an idiot, I did it the same way but forgot to check if 330 was divisible by 50.
      Also, isn't there a more accurate method than this hit and trial sort of method, I mean how long would you go on checking which is divisible, coz sometimes the no. may be too big
      Thanks again

    • @Ennar
      @Ennar Před 4 lety +5

      @@abhavyakeerti8599, you are welcome. Actually, there was no trial and error, we know all the solutions of every linear Diophantine equation, it's precisely what I wrote. Check the wiki page en.wikipedia.org/wiki/B%C3%A9zout%27s_identity for more details.

  • @KurNorock
    @KurNorock Před 4 lety +4

    "We can answer yes with no intensive work required"
    Except for drawing the circle diagram specific to multiples of 7, and then figuring out and memorizing all the patterns.

  • @lfestevao
    @lfestevao Před 4 lety +2

    119 thing is you checked 4 numbers. As an adult, you are used to check the 2s and the 5s unconsciously. If you were used to the 3s as per the rule of algarism addition, this would also be automatic. And finally the 7s you actively check.
    Your vid is a good thing because it gives insight and a visualization for a concept many have abstractly. Which is easier and faster, just like the 2s and 5s check in the decimal base.

  • @PerspectiveInsightReviews

    I looked at this at 7 min and thought this is enough info for a week and then I realized the video is 20 min.
    MY BRAIN EXPLODED

  • @jarrodanderson2124
    @jarrodanderson2124 Před 4 lety +8

    What is the Number Theory book you liked so much? Excellent video btw. I loved the wheel math graphics!

    • @zachstar
      @zachstar  Před 4 lety +7

      Thank you! And I actually used the book 'elementary number theory' by david burton (it says 'revised printing' on the front rather than an edition). I didn't use the exact one I showed a picture of but that just looked more visually pleasing for the video lol. I had found a free online version of the one I used and thought it was well written.

    • @jsdp
      @jsdp Před 4 lety

      @@zachstar Cheers. Definitely going to check the book out now!

    • @Aruthicon
      @Aruthicon Před 4 lety

      My statistics teacher lent Burton’s book to me a while ago, and I can say that it is amazing.

  • @Supremebubble
    @Supremebubble Před 4 lety +7

    Digital Roots are just another reason I loved the game 999.

  • @leecaraway706
    @leecaraway706 Před 4 lety +1

    Ben doing this for 60 years, best I have ever seen!

  • @alestane2
    @alestane2 Před 4 lety +1

    3:50 You actually check all 4 primes, not just two. Just because you verify 2 and 5 using a simple divisibility rule doesn't mean this is not a check. And there is another such rule for 3, so you don't need to actually do the division for that one either (the sum of the digits of a number divisible by 3 is also divisible by 3). The same rule eliminates 3 at 4:10, and you can also use the rule for 11 (the alternated sum of the digits of a number divisible by 11 is also divisible by 11) to eliminate it.

  • @brodysdaddy
    @brodysdaddy Před 2 lety +3

    3:45 you can do a faster check on if a number is divisible by 3. Add up the digits that make up the number....119 would be 1+1+9=11...11 is not divisible by 3 so 119 isn't. 219 is or 120 ....

  • @sadaghem2151
    @sadaghem2151 Před 3 lety +3

    I didn't understand anything but now I can say things nobody else is able to understand too

  • @yopenzo
    @yopenzo Před 3 lety

    great work pal, thank you very much!

  • @dew3968
    @dew3968 Před 3 lety

    This is magnific! Keep it up, man!!!

  • @ugexcelsus4812
    @ugexcelsus4812 Před 4 lety +13

    Tbf this could be helpful to how education could be taught

    • @MMABeijing
      @MMABeijing Před 4 lety +1

      tbf as "to be fair"? strange use in that context

  • @domc3743
    @domc3743 Před 3 lety +6

    119 isn't prime, consider writing 119 as 144 - 25 that is a difference of two squares then we have the factorisation (12+5)(12-5) = (17)(7)

    • @dataandcolours6284
      @dataandcolours6284 Před 2 lety +1

      Great observation! It's called Fermat factorization and it's one of the the reason why it's important that the two primes p and q that makes up the composite n in RSA-encryption shouldn't be too close to each other.

  • @johneod7860
    @johneod7860 Před 4 lety

    Eye opening. Falling in love with math again. Thanks

  • @dibujodecroquis1684
    @dibujodecroquis1684 Před 4 lety

    What an amazing video! Thank you so much!

  • @BangMaster96
    @BangMaster96 Před 4 lety +5

    Could you do a video on Tensors, like Rank 3, and Rank 4 tensors if possible, i am very confused on understanding their notations and visualizing them

    • @tomkerruish2982
      @tomkerruish2982 Před 4 lety

      Gravitation by Misner, Thorne, and Wheeler, suggests that tensors be thought of as linear machines with slots for vectors and 1-forms. Don't worry about trying to visualize a high-dimensional array of numbers.

    • @seriouscat2231
      @seriouscat2231 Před 4 lety

      The tensors are not there because the theory of gravity would require them, but to hide problems in the theory. The expectation is that once you have invested so heavily in the math, you have no desire to turn around and be critical of it.

  • @Katharinka007
    @Katharinka007 Před 4 lety +4

    Exactly my Algebra 2 exam... I'm still having nightmares. :D

    • @itsmidtrib1569
      @itsmidtrib1569 Před 4 lety

      Arrow princess I’m 6 years out of high school and still have nightmares about algebra 2

  • @Sarah-re7cg
    @Sarah-re7cg Před rokem

    Ahh thank you so much, it makes it so much more intuitive

  • @mrunderhill3970
    @mrunderhill3970 Před 2 lety

    This was very cool - thanks for doing this.

  • @superheaton
    @superheaton Před 4 lety +12

    original idea from Nikola Tesla's prime numbers, 3, 6, 9, damn she's fine.

  • @bahrainiapple3458
    @bahrainiapple3458 Před 4 lety +3

    Im a student in Math HL Analysis and Approaches for IB. Is this coming? Cuz if it is i need to brace for impact...

  • @info2pragya
    @info2pragya Před 4 lety

    ultimate explanation. i am glad that this video appears in my search.

  • @OG-O226
    @OG-O226 Před 4 lety

    Awesome video 👌, definitely helped me see numbers in a new way. Very grateful to you bro 🙏.

  • @ReelFactoryPro
    @ReelFactoryPro Před 2 lety +3

    Math videos relieves me of insomnia.

  • @hetgenie
    @hetgenie Před 4 lety +4

    1:06 you don't need a calculator to see if a number is divisible by three. The digits 1+1+9 don't add up to a number that is divisible by three. So the number itself equally isn't.
    EDIT: 13:17 Nevermind ;-)

    • @UTU49
      @UTU49 Před 2 lety +1

      I've used this test for divisibility by 3 as long as I can remember. I might have learned it when I was about 10 or 12 or 14. Not sure.
      One of my best friends did not know the test, and he had taken 2nd year university courses in stats, calculus, and linear algebra. I can't imagine going through the amount of math I have in my life without knowing the test for divisibility by 3.

  • @tiagocomputacao
    @tiagocomputacao Před 23 dny

    Finally! This video made me understand why modular arithmetic is useful.

  • @johnnysparkleface3096
    @johnnysparkleface3096 Před 4 lety +4

    I was keeping up with you nearly all of of the way through the first second.

  • @Naitasm
    @Naitasm Před 4 lety +3

    14:02 "A slightly more official term for working with 9's though, is the digital root."
    *Nonary series flashbacks*

    • @awpbaldyMC
      @awpbaldyMC Před 4 lety +2

      sudoku flashbacks

    • @rocketgames9873
      @rocketgames9873 Před 2 lety

      Digital Root
      *Deltarune ch. 2 before-spamton teacups flashbacks*

    • @manioqqqq
      @manioqqqq Před rokem

      @@rocketgames9873 Don't remind m- Oh. That's my alt.

  • @dcterr1
    @dcterr1 Před 3 lety

    Very good explanation of modular arithmetic.

  • @Alloran
    @Alloran Před 4 lety

    This is a fantastic video that I am much too hungover to appreciate fully. Kudos.

  • @sb-hf7tw
    @sb-hf7tw Před 4 lety +5

    I can't afford subscription of briLLiant.😢 Would you like to make more videos on BRILLIANT COURSES plzzzzz!!!!!!!!🙏🙏🙏
    Also good work ""major prep"", keep it on. Best wishes.
    One last thing- I barely like a video but I liked it...👍👍👍👌👌
    Actually this is the last one---😊
    ###BRILLIANT type courses should be included AND showed in graduation level in UNIVERSITIES...

    • @patheticgeek
      @patheticgeek Před 4 lety

      when you cant afford brilliant so you ask a person to make videos on its topics
      modrem problems require modren solutions...

    • @sb-hf7tw
      @sb-hf7tw Před 4 lety +1

      I just asked cuz major prep had described a mathematical topic in such a fabulous way. Just it.