Pascal's Triangle - Numberphile

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  • čas přidán 9. 03. 2017
  • Just a few fun properties of Pascal's Triangle - discussed by Casandra Monroe, undergraduate math major at Princeton University. Filmed during the MSRI-UP summer program.
    Numberphile is supported by the Mathematical Sciences Research Institute (MSRI): bit.ly/MSRINumberphile
    We are also supported by Science Sandbox, a Simons Foundation initiative dedicated to engaging everyone with the process of science.
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Komentáře • 1K

  • @austynhughes134
    @austynhughes134 Před 7 lety +588

    I love how you guys constantly interview people who have a genuine love of mathematics! It makes these videos so amazing.

  • @ImAllInNow
    @ImAllInNow Před 7 lety +243

    Want another pascal's triangle pattern? Take the top right diagonal (1, 1, 1, ...) and treat it as if it was a decimal number with the decimal point between the first two numbers (1.11111...). Now square that number. You get 1.234567... which equals the second diagonal. Cube it and you get 1.3717421... Which is the third diagonal (you have to smush the numbers together the same was as 1,5,10,10,5,1 = 161,051).
    Now this works in bases other than 10. If you treat 1.11111 as a binary number it equals 2 (same way 1.9999... = 2 in decimal). Now 2^2 = 4. So we know that 1.234567... in binary equals 4. Written as an infinite sequence, 1.23456 in binary is 1 + 2/2 + 3/4 + 4/8 + 5/16 + 6/32 + ... which indeed equals 4!
    This pattern even has a connection to another Numberphile video, Grafting Numbers, and it's truly remarkable, although this comment section is too small to contain it.

  • @ExplosiveBrohoof
    @ExplosiveBrohoof Před 7 lety +191

    For anyone interested in why these patterns emerge:
    *Pascal's Triangle encodes n choose k:* This arises from the fact that _C(n, k) = C(n-1, k-1) + C(n-1, k)._ This can be solved algebraically (note that _C(n, k) = n!/(k!(n-k)!)),_ but there's a combinatorial argument to it as well. Say you have _n_ different ice cream flavors and you want to choose _k_ of them for your super tall ice cream cone. Then you can consider two distinct cases: the combinations with chocolate, and the combinations without chocolate. If you include chocolate, then you have _n-1_ flavors left and you need to choose the remaining _k-1_ flavors. If you don't include chocolate, then you still have _n-1_ flavors, but you still have _k_ flavors to choose from as well. Hence, when you add them together, you should get the total _C(n, k)_ combinations. Because of this identity, you can inductively show that Pascal's Triangle encodes _n_ choose _k._
    *The rows are consecutive powers of 2:* Remember that if you want to choose _k_ objects from _n_ items, you go down to the _n_ -th row in the triangle and you go over by _k._ This means that the _n_ -th row will be the numbers _C(n, 0), C(n, 1), C(n, 2), ..., C(n, n)._ Now, consider the total number of ways to choose _n_ objects, regardless of the number of items you choose. This will be the sum of all of the cases where you choose _i_ objects for _0

    • @GerSHAK
      @GerSHAK Před 7 lety

      +

    • @GABRIELFILMSTUDIOS
      @GABRIELFILMSTUDIOS Před 7 lety +3

      Arbitrary Renaissance Thanks! I'm going to try to come up with an explanation myself for the ones I did not know before actually reading your comment though.

    • @ExplosiveBrohoof
      @ExplosiveBrohoof Před 7 lety +4

      When I say it takes a bit of complex induction to work out the Fibonacci pattern, I just mean that it's tough to rigorously describe. The intuition is really easy like you said: the first diagonal grabs all the left sums and the second diagonal grabs all the right sums.
      Regarding Fermat, that's really interesting! Thanks for taking the time to share your discoveries.

    • @breathless792
      @breathless792 Před 7 lety +3

      I found a simpler way to describe it:
      Consider a string of ones and zeros as both a Pascals triangle row (in mod 2) and as a binary number.
      Given that take the following string
      1000…0001 (between the 1’s on either side are all zeros)
      Each 1 creates its own mini triangle due to the zeros on either side (this partly explains Siepinski’s triangle) at a certain point the two sub triangles will meet, they will meet when the both rows are all the 1’s (i.e. like 1111….111)
      Proof:
      If you consider a row of all 1’s, 1+1=0 (mod 2) so all will be zeros in the next row apart from extra 1’s placed at either side I.e it creates 1000…0001 so the previous row to 1000…0001 will be all 1’s with 1 less of them.
      Now the row with the 1’s can be called row X (which means it has X terms) now if you take each sub triangle to that row (the 1000…0001 is row 1 of the mini triangle) so at this point you will at row 2X so 2X terms so when you put the two row X’s together there are no 0’s in between)
      Now that you’ve done 2X rows you have all 1’s again so it creates another 1000…0001
      Now as binary numbers each row can be factorised as the sub triangle row (as a binary number) multiplied by the 1000…0001 and that represents multiplying that number by all previous rows
      Finally to prove that the numbers you multiply each past term are Fermat numbers
      Proof:
      First the number is in the form 1000…0001 (in binary) which means it’s 1 more than a power of 2 (which in binary is 1000….000)
      Second you take the “111…111” number and duplicate it so the number of 1’s is doubled and if you add 1 it becomes a power of 2 with the same number as zeros as the number that had 1 added had 1’s, add 1 again and it has the same number of digits, and adding the first 1 increased it digits by 1 so if the 111…111 was row X then 1000…0001 (the number obtained by adding 2) it the next row of the Triangle and the number in the middle(not the triangle the value since there is difference is 2) is a power of 2 with a number of 0’s as explained above
      Since you started with 1 on its own (at the top of the triangle) and each time you doubled it
      (1,11,1111…etc) it means that the number of 0’s in the power of two (and therefore the power) is a power of 2 so it is in the form 2^(2^N) since this number has one added to create the number you multiply by, its (2^(2^N))+1 which is the definition of a Fermat number

    • @hyh2012
      @hyh2012 Před 6 lety +2

      Another way to prove the Hockey Stick Theorem:
      The corresponding identity is:
      C(n,n) + C(n+1,n) + ... + C(n+k,n) = C(n+k+1,n+1) (n,k∈N) (The other direction is just symmetry of Pascal's triangle C(n,r)=C(n,n-r))
      The identity can be proved using a combinatorics argument:
      Number of ways to choose n + 1 items from a set of n + k + 1 elements: C(n+k+1,n+1)
      But this can be computed in another way by considering cases:
      including element 1 - C(n+k, n)
      excluding element 1, including element 2 - C(n+k-1, n)
      excluding elements 1, 2 including element 3 - C(n+k-2, n)
      ...
      Keep going with this pattern until:
      excluding elements 1, 2, ..., k, including element k + 1 - C(n, n)
      If keep going excluding more than k elements then it is impossible to choose n + 1 from n + k +1 elements. So we have covered all cases here.
      Equating the 2 methods of computing number of ways to choose n + 1 items from a set of n + k + 1 elements gives the identity.

  • @3zehnutters
    @3zehnutters Před 7 lety +302

    You can verfy if a number n is prime by looking in the n-th row and checking if every number(beside the 1´s) in that line is 0 modulo n.

    • @AnastasisGrammenos
      @AnastasisGrammenos Před 7 lety +7

      really? wow

    • @Fightclub1995
      @Fightclub1995 Před 7 lety +8

      So n is a prime factor of every number in the nth row (except the ones). Cool pattern.

    • @ZardoDhieldor
      @ZardoDhieldor Před 7 lety +9

      Pascal's triangle never stops amazing me.

    • @3zehnutters
      @3zehnutters Před 7 lety +3

      i was super excited when i first discovered this pattern myself

    • @nuclearcoconut3664
      @nuclearcoconut3664 Před 7 lety +6

      That makes me wonder...is testing pascal's triangle as efficient as simply testing factors?

  • @AndersHass
    @AndersHass Před 7 lety +77

    00:50 "We can go on as long as we want and for me it is when the first double digit shows up because that is when adding gets hard." lol

  • @ravneetsingh1499
    @ravneetsingh1499 Před 7 lety +756

    Fibonacci numbers in Pascal triangle..... JUST AWESOME

  • @jenecomprends
    @jenecomprends Před 7 lety +466

    Please ramble on more about this triangle!

    • @justinward3679
      @justinward3679 Před 7 lety +27

      Did you know that if you put a point at every edge of Pascal's triangle you get a triangle?

    • @PhilBagels
      @PhilBagels Před 7 lety +25

      The first diagonal is all 1's. The second diagonal is the natural numbers. The third diagonal is the triangular numbers. The fourth diagonal is the tetrahedral numbers. The fifth diagonal is the pentachoronal numbers. etc. The nth diagonal is the n-1-dimensional simplex numbers.

    • @ZardoDhieldor
      @ZardoDhieldor Před 7 lety +16

      Except you don't, because it's infinite and only has one corner and two edges.

    • @danielketterer9683
      @danielketterer9683 Před 7 lety

      jenecomprends exactly. more like please don't

    • @TheWeepingCorpse
      @TheWeepingCorpse Před 7 lety +2

      Zardo Dhieldor an edge if defined by two vectors, so maybe its a vector and two rays?

  • @IceMetalPunk
    @IceMetalPunk Před 7 lety +110

    New conjecture: Pascal's triangle encodes literally everything that can be encoded.

    • @angelmendez-rivera351
      @angelmendez-rivera351 Před 5 lety +9

      IceMetalPunk Sure it can. Since Pascal's triangle is of order Aleph(0), the set of things it encodes is of the size of the set of the real numbers, Aleph(1). So at the very least, it must encode almost everything.

    • @samuelking1624
      @samuelking1624 Před 3 lety +14

      IceMetalPunk's conjecture: "Pascal's triangle encodes literally everything that can be encoded." would be very funny to see in a paper. You should try to proove.

    • @ingenuity23
      @ingenuity23 Před 2 lety +3

      @@samuelking1624 a hundred years later, its a millenium prize problem, and we all were here to witness history right before our eyes

  • @thanhgoal8711
    @thanhgoal8711 Před 7 lety +46

    I love it when mathematicians can't hide the hype while talking about numbers!!!!
    All of this is adorable!!!! XD

  • @Xeroxias
    @Xeroxias Před 7 lety +25

    So cool to see an undergrad on numberphile

  • @khayanjumbe1462
    @khayanjumbe1462 Před 2 lety +2

    I used to watch you guys when I was like 6 or 7 and now I can finally understand what you are talking about

  • @RodeyMcG
    @RodeyMcG Před 7 lety +9

    11:09 Brady's little exhale when he gets what's going on is the exact same reaction I made :D Very cool!

  • @GerSHAK
    @GerSHAK Před 7 lety +3

    One of my favourite Numberphile videos in a long time. I knew Pascal's triangle, but I had no idea it showcased this many math phenomenons. Sierpiński's triangle is what blew my mind the most.

  • @gavinmann4152
    @gavinmann4152 Před 4 lety +9

    12:15 'there are still other things i can ramble on about....'
    Me: TELL ME NOWWWW

  • @Eltro920
    @Eltro920 Před 7 lety +8

    Finally, a video about Pascal's triangle, and it's amazing.

  • @pyotrleflegin7255
    @pyotrleflegin7255 Před 7 lety +6

    Thank you -- your enthusiasm is infectious!

  • @alonkellner5375
    @alonkellner5375 Před 7 lety +6

    The nth row in the Pascal triangle discribes the geometrical properties of an n dimensional simplex, for instance, the 3D simplex is a tetrahedron, a tetrahedron has 4 vertices, 6 edges, and 4 faces, which is the third row.
    (**to get the full row count 1 zero dimensional shape, or an 'empty' shape, and 1 3D cell, that gets you to 1,4,6,4,1)

  • @austinbryan6759
    @austinbryan6759 Před 4 lety +11

    I think it's pretty cool how, with Pascal mod 2, you can see how adding odds and evens work.
    0 + 0 = 0
    1 + 0 = 1
    1 + 1 = 0
    Which maps to the classic rules of adding evens and odds.
    What's more remarkable is that it also follows adding in single digits in binary. 1 + 1 = 10 in binary but if you make the results only the ones place then it's 0

  • @VirtualMarmalade
    @VirtualMarmalade Před 7 lety +23

    This is like magic. I didn't realize Pascal's Triangle had so much in it!

  • @UMosNyu
    @UMosNyu Před 7 lety +7

    6:26 is my favorite thing. All the mods. Had a great maths teacher who showed this pattern to us.

  • @NeemeVaino
    @NeemeVaino Před 7 lety +6

    Reminds a childhood discovery -
    To calculate 5th row for example, without adding up previous ones, just multiply 1 * 5/1 * 4/2 * 3/3 * 2/4 * 1/5.
    Note the numerator decreasing while denominator increases.
    So generally, k-th number in the n-th row is n!/(k!(n-k)!)

    • @yosefmacgruber1920
      @yosefmacgruber1920 Před 5 lety

      We know that the 1st number in the 5th row is 1. So let's try and see if that is what your formula produces. 5!/(1!(4!)) = 5. Oops. 5 ≠ 1. Are you considering the 1 to be in the k=0 position and the 5 to be the k=1 position? It also appears that you are considering the top of the triangle to be of row n=0?

    • @angelmendez-rivera351
      @angelmendez-rivera351 Před 5 lety +1

      Yosef MacGruber Yes. That is actually the definition of the Pascal triangle. The topmost row is the 0th row and the leftmost diagonal is the 0th diagonal. The adding recursion is not part of the definition, that's just an easy construction that works due to the properties that choose(n, k) as a function satisfies.

    • @angelmendez-rivera351
      @angelmendez-rivera351 Před 5 lety

      Yosef MacGruber Therefore, your counterargument is incorrect.

  • @gdsu234
    @gdsu234 Před 7 lety +8

    I absolutely love this channel. Everytime the poorly thought out school curriculum kills my interest in math, one of these videos fires it up again. Thanks guys!

  • @VernePhilleas
    @VernePhilleas Před 5 lety +1

    I love Casandra Monroe's zeal for mathematics. This video was inspiring and enriching. I love Pascal's Triangle and all the mathematical intricacies it reveals!

  • @Luisa_1743
    @Luisa_1743 Před 7 lety +1

    This video is absolutely amazing!!! Thank you so much for bringing these curiosities about Pascal's triangle!

  • @pythagorasaurusrex9853
    @pythagorasaurusrex9853 Před 7 lety +3

    Great stuff! I knew most of the properties from the beginning of the video. But I NEVER heard about the fact that Fibonacci's row is encoded in the Pascal triangle. Mind blowing!!

  • @pancakeparliament
    @pancakeparliament Před 7 lety +3

    im so happy numberphile finally did a video on pascal's triangle

  • @randomuser778
    @randomuser778 Před 7 lety +1

    Fantastic episode! Bloody brilliant. Love the presenter's enthusiasm too!

  • @painovoimaton
    @painovoimaton Před 3 lety

    It is really quite a remarkable thing. So many patterns within it! Pascal's triangle really exemplifies mathematical beauty to me, it has so much going on within a simple rule.

  • @aosteklov
    @aosteklov Před 7 lety +214

    she is so cool

  • @Zeezjay
    @Zeezjay Před 7 lety +164

    what if you extended the triangle to a tetrahedron or any simplex of n dimensions?

    • @Sejiko
      @Sejiko Před 7 lety +23

      wow this is mind blowing stuff and i have some ideas.... thank you man.

    • @connorp3030
      @connorp3030 Před 7 lety +31

      I've heard they've done that for a trinomial distribution pattern, pretty neato

    • @Sejiko
      @Sejiko Před 7 lety +8

      Imagine a programm that represent this pattern as tetrahedron in a 3d world and highlight some numbers.

    • @abrasivepaste
      @abrasivepaste Před 7 lety +28

      Look up Pascal's Pyramid

    • @wellme3367
      @wellme3367 Před 7 lety +9

      You get the multinomial coefficients.

  • @RichardDominguezTheMagicIsReal

    honestly what I really like it how excited she is to explain the triangle, her enthusiasm had me interested

  • @slebeig3035
    @slebeig3035 Před 7 lety

    It's great to have those kind of videos of brilliant people for free available for everyone, Thank you!

  • @imveryangryitsnotbutter
    @imveryangryitsnotbutter Před 7 lety +34

    A more illustrative way to write out the part at 4:47 would be:
    100,000
    050,000
    010,000
    001,000
    000,050
    000,001
    -------------
    161,051

  • @estelonb.j.eastham3195
    @estelonb.j.eastham3195 Před 7 lety +10

    When I saw the Fibonacci Sequence in that I actually said, "It's so beautiful!"

  • @torlachrush
    @torlachrush Před rokem +1

    Casandra Monroe's enthusiasm is inspiring.

  • @CacchiusMan
    @CacchiusMan Před 7 lety

    This video just gave me even more things i did not know about Pascal's triangle. Like, i knew about the diagonal sequences, the powers of two and the factorial coefficient, but i did not knew about the rest. Truly amazing how many things this triangle hides :D Thank you very much brady :)

  • @NickKravitz
    @NickKravitz Před 7 lety +21

    Around the 8th grade in US we learn Pascal's triangle to solve n choose k problems. In high school we learn the short cut formula for each entry: n choose k equals n! / (k!(n-k!)). In university we learned binomial formula containing the n choose k term. This is by far the most practical use for Pascal's triangle.

    • @nathanisbored
      @nathanisbored Před 7 lety +6

      i did not learn pascal's triangle in 8th grade in california, or ever in school for that matter. i also never learned the choose function in school, definitely not high school. i did learn binomial theorem in calculus 2 later on tho

    • @tupactheory3739
      @tupactheory3739 Před 7 lety

      I first was introduced to Pascal's Triangle in the third grade... when I was eight.

    • @anthonyderose6443
      @anthonyderose6443 Před 7 lety

      Nick Kravitz I learned Pascal's triangle and binomial theorem as a junior in HS to expand expressions. I always chose to use pascals in my work. Never understood binomial theorem.

  • @TakeWalker
    @TakeWalker Před 7 lety +8

    She's wearing an Autobot shirt, she is immediately the best guest you've ever had. :D

  • @Madsy9
    @Madsy9 Před 7 lety +1

    Enjoyed both the topic and the new speaker. Hope we'll get more episodes with Casandra in the future :)

  • @maikopskoy
    @maikopskoy Před 7 lety

    Wow I dont regret watching this. well done, I'm quite suprised to find this out. Thank you

  • @leobekayombo8087
    @leobekayombo8087 Před 7 lety +5

    Smart mathematician doing beautiful stuff!!!

  • @clover7359
    @clover7359 Před 7 lety +3

    If you go down the diagonals, you get n dimensional triangle numbers.
    For example, 0 dimensional triangle numbers are 1, 1, 1, 1, ... etc
    1 dimensional triangle numbers would be 1, 2, 3, 4, 5, 6, 7, etc
    2 dimensional triangle numbers would be 1, 3, 6, 10, 15, 21, 28, 36, etc
    Then the 3 dimensional triangle (pyramidal) numbers would be 1, 4, 10, 20, 35, 56, etc and so on. You can keep going in higher dimensions if you just keep going along the next diagonal.

  • @seanehle8323
    @seanehle8323 Před 7 lety +1

    I love her passion and energy.

  • @vijayetc
    @vijayetc Před 7 lety

    Extremely interesting. I got curious and searched online for PI and e, and no surprises, they are hidden in this triangle as well. Amazing!. Thanks for this.

  • @enlongchiou
    @enlongchiou Před 7 lety +56

    One more interesting thing for Pascal's triangle of (x-1)^n, change sign from 3rd term on at every row turn out is trivial zero of zeta function at s=1, -2 = 1 -2 - 1, -4 = 1 - 3 -3 +1, -6 = 1 - 4 - 6 + 4 - 1, -8 = 1 - 5 - 10 + 10 - 5 + 1,etc...-2n, .nontrivial zero which are extension of trivial zero obey same rule have 2^n series, (2*n)!/(n!)^2 of moment of nontrivial zero 1,2,6,20.. right at middle line of triangle, let bottom of triangle from 0 to 1 at x-axis, 1,2,6,20.. right at x = 1/2 line as Riemann hypothesis predicted.(Euler product of (p-1)/p is 0.04875 from 2 to 99991, take 2^9632 - 1 of mod(10^10,po)/po get 34490000, 0.04875*10^10/34490000 =14.13 po is all possible combination from 2 to 99991, 2nd 0 ,21.02 = 487500000/23190000 get without 2., 487500000/19500000 = 25 3rd zero of zeta function without 2 and 3, so on...25*(1/2)(2/3)(4/5) + 1/2 - 1/6 - 5/10 + 25/30 + 1/3 - 10/15 +0/5.+3 -1 = 9 prime number counting until 25.)

    • @anon8857
      @anon8857 Před 7 lety +3

      hey enlong chiou! i remember you from g+ ! ur awesome!!

    • @camilogallardo4338
      @camilogallardo4338 Před 7 lety +5

      enlong chiou give us the nontrivial zeros!

    • @Israel2.3.2
      @Israel2.3.2 Před 7 lety +10

      A favorite of mine. If this is confusing just google 'Faulhaber's formula.'
      Let x/(exp(x) - 1) = a + (b/1!)x + (c/2!)x^2 + (d/3!)x^3 + (e/4!)x^4 + (f/5!)x^5 + ... [and let mx^n = (m)*(x^n)]
      Then
      1^0 + 2^0 + 3^0 + ... + n^0 = (1/1)(an)
      1^1 + 2^1 + 3^1 + ... + n^1 = (1/2)(an^2 - 2bn)
      1^2 + 2^2 + 3^2 + ... + n^2 = (1/3)(an^3 - 3bn^2 + 3cn)
      1^3 + 2^3 + 3^3 + ... + n^3 = (1/4)(an^4 - 4bn^3 + 6cn^2 - 4dn)
      1^4 + 2^4 + 3^4 + ... + n^4 = (1/5)(an^5 - 5bn^4 + 10cn^3 - 10dn^2 + 5en)
      1^5 + 2^5 + 3^5 + ... + n^5 = (1/6)(an^6 - 6bn^5 + 15cn^4 - 20dn^3 + 15en^2 - 6fn)
      etc.
      Notice the 'truncated' version of Pascal's triangle.

    • @iustinianconstantinescu5498
      @iustinianconstantinescu5498 Před 7 lety +1

      enlong chiou Amazing!!!

    • @slipknnnot
      @slipknnnot Před 7 lety

      Says the anonymous guy called "Fish Bones"

  • @martinepstein9826
    @martinepstein9826 Před 7 lety +7

    Here's how I heard about the relation between Pascal's triangle and Fibonacci numbers.
    Problem: You're climbing a ladder n rungs high and you always have a choice of climbing 1 or 2 rungs at a time (let's call these actions single steps and double steps). How many ways are there to climb the ladder?
    One approach to the problem is to use combinatorics: first find the number of ways to climb if you never take a double step, then the number of ways if you only take 1 double step, then 2, etc and then add it all up. This sum corresponds to adding terms along a shallow diagonal of Pascal's triangle.
    A second approach is to use recurrence: to climb n rungs you must first climb n-1 rungs and then take a single step OR climb n-2 rungs and then take a double step. So if f(n) is the number of ways to climb n rungs then we have f(n) = f(n-1) + f(n-2) which gives us the Fibonacci sequence.

    • @martinepstein9826
      @martinepstein9826 Před 7 lety +1

      I remember reading that this problem was first solved by composers of Indian classical music who wanted to know how many ways there are to, say, fill a bar of music with 8th and 16th notes. Not in those western terms of course.

  • @kateinmadison
    @kateinmadison Před 7 lety

    I've loved Pascal's Triangle since I first learned about it in 7th grade. I had so much fun playing with it in mod 2, mod 3, etc. Different pattern each time!

  • @old-bitprogaming4857
    @old-bitprogaming4857 Před 7 lety

    I love this channel, even thought I knew this I loved how well it is explained

  • @TheKrevit
    @TheKrevit Před 7 lety +437

    nth

  • @jetlag1488
    @jetlag1488 Před 7 lety +894

    Illuminati confirmed

    • @hiveinsider9122
      @hiveinsider9122 Před 7 lety +25

      Get back to being a meme on Etho's channel! :P

    • @QualityContentX
      @QualityContentX Před 7 lety +1

      We take the Triangle and push it somewhere else

    • @yaseen157
      @yaseen157 Před 7 lety +13

      lol who'd have known you'd leave Etho's channel to find your way to a top comment here?

    • @H0kram
      @H0kram Před 7 lety +6

      Yes. Once again.
      After millions of confirmations.
      This confirms it again.

    • @joeydunn930
      @joeydunn930 Před 7 lety +10

      Are you following me? I just came from Project Ozone #29... :)

  • @briannalove749
    @briannalove749 Před 7 lety

    I first learnt about Pascal's Triangle because of how you can use it in the expansion of brackets with a high power. So if you had (x+a)^5, you would go to Row 5 of the triangle, and each value is a coefficient, in order, so you add that to each product, and list the powers in descending order for x and ascending order for a. Will definitely save a lot of time in exams. In January, I had a summer school for my math this year (to prepare us for senior highschool math) and we looked at other ways it can be used then as well (mainly combinations and permutations - I don't remember which). It's such an amazing mathematical tool.

  • @robertvdhill367
    @robertvdhill367 Před 7 lety

    I love so many things about this video!

  • @llamawaffles5559
    @llamawaffles5559 Před 7 lety +6

    Alright, i have a question if anyone is still reading the comments on this video. I was doing a problem for my Intro Quantum Mechanics class about spin-1/2 particles, and after doing a bit of math, ended up getting what is essentially a 3d square pyramid of numbers (idk if that's right, its 4 triangles, each making a side), except there is no bottom, it just goes on indefinitely as far as you want to extend it (like pascal's triangle). In fact, my professor noticed that the outer triangle of each side of the pyramid IS Pascal's triangle. Which made me curious if there was some overarching recursion relation (or other relation) to predict future rows/squares of the pyramid. If you look at one of the outside triangles, then remove it and look at the triangle beneath it, and continue doing this, this is what you find:
    Triangle 1: 1, 1 1, 1 2 1, 1 3 3 1, 1 4 6 4 1, 1 5 10 10 5 1, etc (Pascals Triangle)
    Triangle 2: 0, 1 1, 4 0 4, 9 2 2 9, 16 10 0 10 16, 25 27 5 5 27 25, 36 56 28 0 28 56 36, etc (what pattern?)
    Triangle 3: 4, 4 4, 1 12 1, 1 15 15 1, 16 8 40 8 16, 64 0 56 56 0 64, etc (my computer cant compute any more)
    Triangle 4: 0, 9 9, 36 0 36, 64 24 24 64, etc (computer cant do anything layer 10 or below)
    Triangle 5: 36, 36 36, etc
    That is all my computer can do, but as soon as you get to layer 10 of the pyramid, i go beyond the Integer limit in C# and i haven't fixed that problem yet, so my computer just gives me either 64 or null. weird bug, but yeah. if you can figure out some pattern, that would be awesome. And for anyone wondering what these numbers are here is the slightly longer story:
    Each layer, or square, of the pyramid corresponds to the spin of a particle, starting with zero. row zero is a spin-0 particle, row 1 is a spin-1/2 particle, row 2 is a spin-1 particle, row 3 a spin-3/2 particle etc. and the numbers each column/row correspond to the probability that the spin will be measured at that magnitude in a direction orthogonal to the currently known spin (the closes thing Quantum Mechanically to "random"). for example, row 3, column 5, in layer 7, of this pyramid corresponds to the probability that a spin-7/2 particle measured to have spin-5/2 in some direction will be measured to have spin-3/2 in an orthogonal direction. Also the probability that a spin-7/2 particle with spin 3/2 will be measured to have spin-5/2 in an orthogonal direction. However, it is easy to see that the rows do not add to unity, and that is because i have removed a normalization constant to make them all whole numbers. the normalization constant for the n-th layer is simply 2^(-n).
    Any more questions i would be happy to answer.

    • @htmlguy88
      @htmlguy88 Před 6 lety

      you could download pari gp and try it with high precision. though you may be relating it to pascal's simplex. en.wikipedia.org/wiki/Pascal%27s_simplex

  • @nachoqt
    @nachoqt Před 7 lety +4

    I've never seen the Fibonacci pattern before. Mind blowing.

  • @jpphoton
    @jpphoton Před 7 lety

    Brilliant! Keeping the bar high Brady. Tally Ho such a good show!

  • @leonardomaranon
    @leonardomaranon Před 7 lety +1

    When you do it in mod 2, then the number of 1's in each row is always a power of two. Great video!

  • @connorp3030
    @connorp3030 Před 7 lety +6

    Pacals triangle patterns make more sense if you think of each diaganol as a cumulative frequency of the diagonal before it
    0+0+0+0+0+0+0+0+0...
    0+1 +1 +1 +1 +1 +1...
    0+1 +2 +3+4 +5...
    0+1+3+6+10...
    0+1+4+10...
    0+1+5...
    0+1...
    0...
    One of the patterns I found was that the sum of squares up to n=((nC1)x(n+1C2))-(n+1C3)
    so for example, sum of squares up to 4=(4x10)-10
    They're are patterns for individual square numbers and cube numbers too, but they're way to complicated for me to explain. It makes me wonder if they're are patterns for every exponent, and they're just too complicated to find.
    Also pascals triangle can be used to find the constants terms for any binomial expansion, a pascals pyramid can be used to find the constant terms for a nominal expansion.
    Pascals triangle is real neato.

    • @connorp3030
      @connorp3030 Před 7 lety +3

      oh, also the diagonals are numbers which are needed to construct a triangle based shape, so the third row is triangular numbers, the fourth row is tetrahedral numbers, and then whatever the fourth dimentional equivalent is is the fourth row I think.

  • @prateekgurjar1651
    @prateekgurjar1651 Před 7 lety +618

    pascal newton and Einstein were playing hide and seek. Einstein said to newton "found you!" but Newton went and stood in a square of length one meter and said "Hey I am newton per meter square..you found pascal" HAHAHAHAHAH...ha..ha

    • @thatoneguy9582
      @thatoneguy9582 Před 7 lety +3

      Prateek Gurjar I don't get it.

    • @prateekgurjar1651
      @prateekgurjar1651 Před 7 lety +57

      units of pressure is pascal..which is Newton per meter square

    • @sinistrolerta
      @sinistrolerta Před 7 lety +9

      That One Guy "Newtons per meter squared" is a unit of pressure which is also known as Pascal

    • @prateekgurjar1651
      @prateekgurjar1651 Před 7 lety +1

      exactly !

    • @soufian2733
      @soufian2733 Před 7 lety +18

      I think in english we say "square meter" and not "meter sqaure". I could be wrong

  • @sofia.eris.bauhaus
    @sofia.eris.bauhaus Před 7 lety +1

    i once made up a "simplex operator": i generalized triangle numbers for any dimension: (triangle (2-simplex), tetrahedron (3-simplex), pentachoron (4-simplex)). the first operand was the edge length and the second operand was the number of dimension.
    x △ 2 was a triangle number for edge length x and so on. as i wrote down the Cayley table (like a multiplication table) i noticed quite a bit of a pattern. suddenly it struck me that i was writing down Pascal's triangle sideways.
    this was one of the coolest things that ocurred to me. :)

  • @browniesnofrownies4843
    @browniesnofrownies4843 Před 4 lety +1

    Excellent explanations!

  • @joeytje50
    @joeytje50 Před 7 lety +11

    9:00 So... the primes' locations on the Pascal triangle are located exactly on the Fibonacci sequence's locations, ignoring 1. They occur at locations 2, then 3, then 5, and the next one (not imaged) would occur at the 8th row. So that's another way to get Fibonacci from Pascal's triangle.

    • @JeSuisUnKikoolol
      @JeSuisUnKikoolol Před 7 lety +12

      The 8th row is 255 and is not prime. The next prime (257) is the 9th row

    • @ImAllInNow
      @ImAllInNow Před 7 lety +1

      yeah, the primes are at (assuming the top is the 0'th row) locations 1, 2, 4, 8, 16, ...

    • @KafshakTashtak
      @KafshakTashtak Před 7 lety

      They are Fermat primes, and so far we only know 5 Fermat primes. Which means the rest of the 2^n rows doesn't create a prime number as long as we know.

  • @Sagitarria
    @Sagitarria Před 7 lety +9

    it goes waaay back into Hindu, Buddhist, and Jain mathematics as "Mount Meru"
    long before pascal it was known to Pingala in or before the 2nd century BC
    much to explore in it's relationship to cellular automata.

  • @Indian_Ravioli
    @Indian_Ravioli Před 7 lety

    Such a great video.... I know about the triangle since high-school but never knew it had so many properties.

  • @robbes7rh
    @robbes7rh Před 2 lety +1

    Uncanny and completely amazing that what at first blush feels like a children's exercise contains all these other relationships and qualities,

  • @Lockirby2
    @Lockirby2 Před 7 lety +3

    It's cool to see an undergraduate on here. :) Gotta love the enthusiasm!

  • @ErnestMSaenz
    @ErnestMSaenz Před 7 lety +3

    Here's one of the patterns that I've used to teach multiplication to elementary school students:
    0 9, 1 8,2 7, 3 6, 4 5, 5 4, 6 3, 7 2, 8 1, 9 0 In the first column on the left, write the numbers in ascending order from zero up to nine and in the second column in descending order from nine to zero and, presto!, you've got the nine's multiplication table. I have patterns for the fours, sixes, sevens, eights and also division.

  • @PatrickChavez
    @PatrickChavez Před 7 lety +1

    Cassandra, well done. love the topic, loved the delivery!

  • @complex314i
    @complex314i Před 5 lety

    It seems we have the same favorite thing about Pascals Triangle if first means favorite. I love combinations and binomial expansion theorem. The hokey stick and fractal triforce I didn't know about. Awsome.

  • @pedroscoponi4905
    @pedroscoponi4905 Před 7 lety +19

    I always thought pascal's triangle was kind of boring. My mistake! hehe XD
    Has anyone ever tried to apply the same methods to different bases?

    • @pedroscoponi4905
      @pedroscoponi4905 Před 7 lety +2

      I'd love to see what those look like, out of silly curiosity

    • @1987Videolover
      @1987Videolover Před 7 lety

      Indicotherium its happened on every base... if u put a number n on the formula, you get (n+1)^x... x means row..
      for examples..
      n = 3, x = 2, u'll get 1(3^2) + 2 (3) + 1 = 9+6+1 = 16 = 4^2
      n = 4, x = 3, u'll get 1(4^3) + 3(4^2) + 3(4) +1 = 64 + 48 + 12 + 1 = 125 = 5^3
      and so on

  • @Phalc0n1337
    @Phalc0n1337 Před 7 lety +3

    Can you show a Parker Triangle next?

  • @gordonfrohman250
    @gordonfrohman250 Před 7 lety

    Thanks to you i instantly solved a circuits problem involving infinite resistances organized as a pascal triangle. Thanks!

  • @purplewarrior12
    @purplewarrior12 Před 7 lety

    Definitely my favorite Numberphile!

  • @lorenzocecchi6851
    @lorenzocecchi6851 Před 7 lety +5

    in Italy we call it "Tartaglia's triangle"

  • @user-tq8nz5pb7n
    @user-tq8nz5pb7n Před 7 lety +3

    there is also the binomial thing

  • @Intelligenz_Bestie
    @Intelligenz_Bestie Před 7 lety

    love the sound effects at the beginning in this one brady

  • @dlee645
    @dlee645 Před 7 lety +1

    Fascinating presentation. Do more with Casandra.

  • @mojosbigsticks
    @mojosbigsticks Před 7 lety +23

    I'm in love.

    • @mojosbigsticks
      @mojosbigsticks Před 7 lety

      A little bit of both.

    • @NoriMori1992
      @NoriMori1992 Před 7 lety

      Mojos Bigstick A little bit of both what?

    • @mojosbigsticks
      @mojosbigsticks Před 7 lety +1

      There was previous reply asking if I was in love with Ms Monroe or with Pascal's triangle. I'm a little bit smitten with both.

    • @denjam2423
      @denjam2423 Před 7 lety +1

      I was worried you fell in love with the triangle only.

  • @altus1253
    @altus1253 Před 7 lety +43

    *Claimed by Nintendo LLC

  • @xystem4701
    @xystem4701 Před 7 lety +2

    I never get tired of Pascal's triangle :)

  • @SuperDangerousMouse
    @SuperDangerousMouse Před 7 lety

    very cool - thank you Casandra

  • @adrianbornabasic7499
    @adrianbornabasic7499 Před 7 lety +5

    Parker triangle - the new Parker square

  • @BerMaster5000
    @BerMaster5000 Před 7 lety +379

    420 Blaise it

  • @dolphinlink
    @dolphinlink Před 7 lety

    Great energy!

  • @Hitherto90
    @Hitherto90 Před 7 lety

    So many intricate mathematical quirks from such a simple sequence.

  • @HyperQbeMusic
    @HyperQbeMusic Před 7 lety +8

    I wouldn't be surprised if Pi showed up in that triangle in a way… somewhere. 🤔

  • @dQw4w9WgXc
    @dQw4w9WgXc Před 7 lety +75

    The Legend of Zelda reference \(°-°)/

  • @CraigMansfield
    @CraigMansfield Před 7 lety

    I love things like this. They make maths interesting and magical

  • @sergiorome48
    @sergiorome48 Před rokem +1

    I love this, quite useful for my discrete math course

  • @zevonmxic468
    @zevonmxic468 Před 7 lety +4

    Mathimus Prime...

  • @stevethecatcouch6532
    @stevethecatcouch6532 Před 7 lety +3

    Cassandra, it wasn't nice to tease us with three or four Fermat primes without mentioning that the run of primes is interrupted after 2^2^4 + 1.

  • @skyenet
    @skyenet Před 2 lety +2

    I've always loved Pascal's triangle, and I love that it still contains mysteries. Has anyone tried to see what happens if you add another axis of 1's? Will we get something that informs us about trinomials, with for example, rows that sum to powers of 3?

  • @Yerrik
    @Yerrik Před 7 lety

    Spectacular!

  • @MarcoBeri
    @MarcoBeri Před 7 lety +64

    The right name is Tartaglia's Triangle :-)

    • @claudiuacsinte4757
      @claudiuacsinte4757 Před 7 lety +23

      Facciamoci sentire ahaha

    • @matt-vi2pn
      @matt-vi2pn Před 7 lety +12

      Marco Beri quindi non sono l'unico italiano qui

    • @ChristianJiang
      @ChristianJiang Před 7 lety +10

      Ehi, Triangolo di Yang Hui, ci siamo arrivati prima noi :-)

    • @tgvv2980
      @tgvv2980 Před 7 lety +4

      stavo pensando l'esatta stessa cosa... perché questi tizi lo stanno chiamando "triangolo di pascal".....?

    • @hdman511
      @hdman511 Před 7 lety +2

      Volevo proprio scriverlo..

  • @fyukfy2366
    @fyukfy2366 Před 7 lety +46

    I hate when people say "upside down triangle" just because a triangle isn't on its point doesn't make it upside down, it's still just a triangle

    • @JaredFT
      @JaredFT Před 7 lety +7

      fyukfy gaming But the base is on top, so yeah, it's upside down. Your logic only applies to horizontally symmetric shapes like squares, circles, etc.

    • @lowlize
      @lowlize Před 7 lety +17

      Every side of a triangle can be a base, but a vertex cannot. So when a vertex is on the bottom and a side is on the top, you can legitimately say the triangle is upside down.

    • @shorterneilisbored7078
      @shorterneilisbored7078 Před 7 lety +19

      If you flip a table over, it's still a table, but upside down.

    • @fyukfy2366
      @fyukfy2366 Před 7 lety +3

      lowlize but you can't legitimately call it "upside down" or "rightside up" or anything like that because those aren't terms nor are the definitions in geometry. Just because in human society when a triangle is on its base it looks "correct" doesn't mean it is

    • @lowlize
      @lowlize Před 7 lety +3

      I know, but if a side can be called a base there must be a reason, right? Even in abstract geometry we work using our physical intuition of a space with a privileged direction (that defined by gravity), so if it can be useful to construct an immediate visual representation (upside down triangle) without ambiguity, why not use it?

  • @pokestep
    @pokestep Před 7 lety

    Ah what a lovely video, knew most of these but loved everything about it ~

  • @MarcellaCh
    @MarcellaCh Před 7 lety

    The fact that she's so excited about this makes me excited about it too. i love her

  • @Someone-cr8cj
    @Someone-cr8cj Před 7 lety +65

    damnnn Casandra Monroe back at it again with
    a transformers shirt... .rly?

    • @pressplayhomie
      @pressplayhomie Před 7 lety

      Someone My exact sentiments.

    • @CastelDawn
      @CastelDawn Před 7 lety +53

      Would be appropriate if it was a video about primes.

    • @Someone-cr8cj
      @Someone-cr8cj Před 7 lety +1

      yeah not the best shirt for a mathematician to wear... it takes your focus of the actual video

    • @dermathze700
      @dermathze700 Před 7 lety +9

      I didn't even notice it until the 8 minute mark or so.

    • @Someone-cr8cj
      @Someone-cr8cj Před 7 lety

      pure mathematics joke...

  • @TheTruthSentMe
    @TheTruthSentMe Před 7 lety +47

    It's inevitable to find patterns if you look for them.

    • @Sejiko
      @Sejiko Před 7 lety +1

      search for pattern is like a hidden background door in maths.you could find something useful for physiks or other topics.

    • @ramiel555
      @ramiel555 Před 7 lety +57

      especially when they're actually there

    • @Nixitur
      @Nixitur Před 7 lety +21

      There is a world of difference between seeing patterns from random noise and being able to _prove_ there's patterns in something like this.

    • @brokenwave6125
      @brokenwave6125 Před 7 lety +4

      TheTruthSentMe Sure you can choose to select and omit things at your choosing and then find any pattern.
      but when ever single number in a sequence is used, in a systematic way...it's not a made up pattern. it's really encoded in the numbers.
      just like everything in this video.

    • @procactus9109
      @procactus9109 Před 7 lety

      Sometimes you don't even have to focus on finding a pattern. People find patterns that don't really exist everyday almost.

  • @robertilijov8983
    @robertilijov8983 Před 7 lety +2

    I was so happy watching this video

  • @WildStar2002
    @WildStar2002 Před 7 lety

    It's also related to the long-hand method for taking whole-number roots. I don't have time to go into detail, but I stumbled across the relationship when I was trying to figure out how to take third roots by hand. Square roots by hand is related to the 1-2 line as you multiple through and third roots to the 1-3-3 line, and so on, 1-4-6-4 for 4th roots, etc. :-)