Liar Numbers - Numberphile

Поделиться
HTML-код
  • Опубликовано: 16 ноя 2024
  • НаукаНаука

Комментарии • 672

  • @shotguntornado
    @shotguntornado 9 лет назад +1081

    I love how cheeky James got about the $620. "Think of what you could do with all that money!"
    He's my favorite face on this channel.

    • @polsp5812
      @polsp5812 9 лет назад +44

      shotguntornado uhuhuhhhh you could buy yourself a chocolaqte iceream every day

    • @Ricardordz11
      @Ricardordz11 9 лет назад +56

      Pol SP Twice on sundays!

    • @dgeri98
      @dgeri98 9 лет назад +17

      +shotguntornado I think he's the favourite of most subsribers

    • @brrrd5303
      @brrrd5303 8 лет назад +3

      That completely depends on if it is £ or $.

    • @DanDart
      @DanDart 8 лет назад +2

      +MelodyFluff it's $ check it out

  • @anisometropie
    @anisometropie 9 лет назад +1350

    “…is called a fermat liar. Ooooh, it's not really prime, it's lying. It tells me it's prime and it's not. Naughty!”
    James talks are my favorites :)

    • @RiccardoBello98
      @RiccardoBello98 8 лет назад +24

      I wonder what CGPGrey would say about the "Naughty!" part :'D

    • @PebsBeans
      @PebsBeans 6 лет назад +5

      He said that right as I read that

    • @RyanLynch1
      @RyanLynch1 6 лет назад +2

      LOL same

    • @shoaibmohammed3707
      @shoaibmohammed3707 6 лет назад +9

      2:50

    • @lucastsui5415
      @lucastsui5415 6 лет назад +18

      This is a lesson. If you are a number reading this, don’t lie.

  • @crazydrummer4827
    @crazydrummer4827 7 лет назад +393

    This is so Parker Square test.

  • @asdasdasdasd714
    @asdasdasdasd714 8 лет назад +1031

    We need to pay more salary to mathematicians. He almost lost his mind over 620$ :D

    • @schadenfreudebuddha
      @schadenfreudebuddha 7 лет назад +94

      there's probably just something mathematically amazing about the number 620.

    • @00bean00
      @00bean00 7 лет назад +134

      schadenfreudebuddha yes, it's the number that allows you to buy ice cream X days a week, twice on Sundays...

    • @GermanRumm
      @GermanRumm 5 лет назад +3

      Any Nobel man knows that the opposite is true ;)

    • @GermanRumm
      @GermanRumm 5 лет назад +3

      Every nobel man thinks the opposite ;)

    • @phs125
      @phs125 5 лет назад +16

      Depends on where you live.
      I'm a doctor in India and I need to work 2.5 months to earn 620$

  • @jacktumbleweed
    @jacktumbleweed 9 лет назад +229

    I've spent the majority of my weekend watching Numberphile videos. Call me insane, you guys make numbers way more interesting than school ever did. I feel excited to learn again.

    • @irenekay7934
      @irenekay7934 9 лет назад +4

      so true!

    • @isaacheaton1805
      @isaacheaton1805 9 лет назад +21

      +Logan Fehr That's because the brain loves learning. It addicted it learning and it's amazing how school can manage to make it boring for people

    • @irenekay7934
      @irenekay7934 8 лет назад +2

      ***** why would it be?

    • @isaacheaton1805
      @isaacheaton1805 8 лет назад +2

      +Leen B No I don't blame the school for not being able to teach. I would blame the parents that can't punish there children. And I understand that it's difficult to make a lesson interesting when you have people like that.

    • @rick19471
      @rick19471 8 лет назад +8

      +isaac heaton It has been my experience the problem is parents who live to punish their children. and other people's also.

  • @colinmusik
    @colinmusik 10 лет назад +428

    Quickly becoming my favorite youtube channel.

    • @numberphile
      @numberphile  10 лет назад +59

      wow, thanks

    • @colinmusik
      @colinmusik 10 лет назад +32

      Numberphile Don't be so surprised. For someone like me who doesn't have a lot of experience in mathematics, these are absolutely amazing videos. Very inspiring and skillfully made to reveal the awesomeness of mathematics. I think just about any discipline can be presented an a boring manner if you're not particularly clever. Needless to say, you guys are indeed very clever. Thanks so much for doing what you do!

    • @Romeo-qk8tk
      @Romeo-qk8tk 9 лет назад +2

      +Numberphile i love math. im in 4th grade and everyone asks me about math but when i dont know,i come to you

    • @adamledger6836
      @adamledger6836 9 лет назад +1

      +Colin Huggins yep same learnt so much new stuff from this one over the last few weeks

    • @miurkahidalgo4028
      @miurkahidalgo4028 8 лет назад +1

      It's everybody's favorite channel!

  • @armoredp
    @armoredp 8 лет назад +86

    620 dollars, I'm regretting not becoming a mathematician already. It seems to be a life of pure decadence and unequaled wealth.

  • @nerdbot4446
    @nerdbot4446 10 лет назад +218

    $30 at the beginning and now $620? Why they´ve picked such random values? Why not $561? Or $1105? Or $1729?

    • @sieevansetiawan4792
      @sieevansetiawan4792 6 лет назад +25

      Why they pick composite numbers?

    • @josebobadilla-ortiz7405
      @josebobadilla-ortiz7405 3 года назад +5

      They should offer the $ value of the counterexample.

    • @Korpionix
      @Korpionix 3 года назад +3

      @@josebobadilla-ortiz7405 A 7 hour-old reply to a 7 year-old comment with two replies, interesting...

    • @goutamboppana961
      @goutamboppana961 3 года назад

      @@Korpionix with 2 replies?

    • @Firefly256
      @Firefly256 3 года назад +1

      @@josebobadilla-ortiz7405 that’ll probably be the whole earth

  • @acorn1014
    @acorn1014 8 лет назад +412

    Maybe this test is actually for Carmaecal composites, and every prime number is a liar.

    • @imveryangryitsnotbutter
      @imveryangryitsnotbutter 8 лет назад +164

      That's just a conspiracy theorem.

    • @Zwijger
      @Zwijger 5 лет назад +13

      No because the primes are what define the Carmichael numbers. A number that passes this test, but isn't prime, is a Carmichael number. You can't define that without primes.

    • @pasarebird02
      @pasarebird02 5 лет назад +18

      CrazyOrc Someone missed the joke

    • @lonestarr1490
      @lonestarr1490 3 года назад +12

      @@Zwijger Actually, you can. A Carmichael number is a number _n_ that is divisible by some _m < n_ and for all integers _b_ with _(n,b)=1_ satisfies _b^(n-1) = 1 (mod n) ._
      See, no primes here.

    • @rushunnhfernandes
      @rushunnhfernandes 2 года назад +7

      @@lonestarr1490 saying that n is divisible by some m

  • @Borednesss
    @Borednesss 10 лет назад +143

    $630 wouldn't even cover the cost of electricity to compute a counter example I bet haha

  • @captainpalegg2860
    @captainpalegg2860 7 лет назад +61

    It’s 2:43 am, I have class in the morning, I'm a freaking *geography* major…and here I am bingeing Numberphile.

  • @SnackMuay
    @SnackMuay 10 лет назад +93

    James is great. I love all the people you have on this channel, Brady, keep up the good work.

    • @numberphile
      @numberphile  10 лет назад +36

      thanks. will do.

    • @thihal123
      @thihal123 9 лет назад +9

      James is really great.

    • @drinkingthatkool-aid3193
      @drinkingthatkool-aid3193 8 лет назад +9

      +thihal123 Yeah I love his enthusiasm and passion. Many professors in college lack that.

    • @thihal123
      @thihal123 8 лет назад +9

      Moaiz Shahzad A lot of professors in college are not too interested in the pedagogical side of being a professor. The tendency is to prefer the research and writing parts of professorship.

  • @SatinFoxx
    @SatinFoxx 10 лет назад +71

    Twice on sundays!? *sets to work*

  • @sbrunner69
    @sbrunner69 3 года назад +5

    How wonderful of a person is Dr Grime! What a fantastic likable human. I wish I could always be around people like him.

  • @merlinmagnus873
    @merlinmagnus873 9 лет назад +262

    How do you get a mathematician to solve a difficult problem? Offer a years supply of Klondike bars! That will get it solved fast.

    • @stevenxu5747
      @stevenxu5747 7 лет назад +14

      Clearly superior than offering $1M. We would have proven the RH by now, damn it! :)

    • @unpaintedcanvas
      @unpaintedcanvas 6 лет назад +8

      What would you do for a Klondike bar?

    • @zanti4132
      @zanti4132 5 лет назад +10

      It's a little known fact that the guy who proved Poincare's Conjecture didn't actually refuse the million dollar prize, he just asked to be paid in Klondike bars.

    • @elvicash
      @elvicash 2 года назад

      How many Klondikes bars in a years supply?

  • @patjohbra
    @patjohbra 8 лет назад +48

    One day I hope to find someone that makes as happy as primes make Dr. Grimes

    • @PoweDiePie
      @PoweDiePie 7 лет назад +11

      He should change his name to Dr. James Prime

    • @Vezur-MathPuzzles
      @Vezur-MathPuzzles 2 года назад +1

      @@PoweDiePie Grime is fine. He can make a show called "Grime Prime Time".

  • @47571660
    @47571660 10 лет назад +116

    Running time: 7:09
    709 is a prime
    I see what you did there.

    • @myrus5722
      @myrus5722 7 лет назад +6

      Waxwing Slain Its 7:08 after the update...

    • @panda4247
      @panda4247 7 лет назад +28

      it's a Parker prime then
      (sorry, I could not resist)

    • @sadchicken5282
      @sadchicken5282 4 года назад

      Insert Channel Name o

  • @miakablan8792
    @miakablan8792 10 лет назад +32

    i am in love with this guy

    • @gohan12991
      @gohan12991 7 лет назад

      mia kablan lol i read your name as mia khalifa

  • @nowneothanielverse
    @nowneothanielverse 8 лет назад +201

    Sometimes i wonder after watching a numberphile video
    i ask my self. Am i a prime?

    • @LazaroCarvalhaes
      @LazaroCarvalhaes 7 лет назад +42

      "Prime" in portuguese is translated as "cousin", so if you aren't, just start a family in Brazil.

    • @3003DaRkNeSs1998
      @3003DaRkNeSs1998 7 лет назад +5

      Lázaro Carvalhaes not only in portuguese but also in spanish.

    • @JonWonders
      @JonWonders 6 лет назад +3

      I was born in 1999, which is a prime number. I guess I'm a prime.

    • @jauume
      @jauume 6 лет назад +2

      Luis Espinoza Cousin in spanish is primo. Close enoguh I guess

    • @Sunspot1225.
      @Sunspot1225. 6 лет назад

      *ItsAMb * if you have to ask your not.

  • @surrog
    @surrog 10 лет назад +11

    Thank you brady for adding subtitles to your videos, I have shown your channel to several hearing-impaired friends and they absolutely love it =)

  • @coyraig8332
    @coyraig8332 4 года назад +1

    This theorem works like the scientific method: question (is this integer a prime number?) --> hypothesis (if it is, then it passes this test) --> experiment (plug it in) --> observation (did it work?) --> conclusion (it did(n't), so it is(n't) a prime). And like science, it isn't perfect. It's just the best we have.

    • @xavierstanton8146
      @xavierstanton8146 3 года назад

      Well Fermat's Little Theorem just says that if p is prime, then the test works. All this video shows really is that the converse isn't true, not the theorem itself. I get what you're saying though

  • @Friedeggonheadchan
    @Friedeggonheadchan 10 лет назад +69

    I want Mr. Grimes to call me naughty, over and over again.

  • @TheReaverOfDarkness
    @TheReaverOfDarkness 10 лет назад +2

    One way to check if a number is prime is to try dividing it by everything up to its square root.

  • @addeyyry
    @addeyyry 10 лет назад +11

    The thumbnail is brilliant...

  • @inthefade
    @inthefade 2 года назад +2

    101101 is such a cool Carmichael number.

  • @VickyBro
    @VickyBro 10 лет назад +1

    I love this guy....always brings a smile to my face. And thanks to Brady.

  • @sachsenschnitzel6552
    @sachsenschnitzel6552 10 лет назад +1

    at the beginning he said, that 1

  • @kamrunnesa5769
    @kamrunnesa5769 4 года назад +1

    Watching numberphile videos and scrolling its comment box make my day.

  • @DevonBernard
    @DevonBernard 10 лет назад +5

    Great video guys! I always love hearing your new math facts. Keep up the great work!

  • @aidanivesdavis
    @aidanivesdavis 9 лет назад +64

    James is hilariousxD

  • @metleon
    @metleon 10 лет назад +2

    1 actually follows Fermat's Little Theorem perfectly (a^1 - a = 0) but also isn't a prime number. That means the theorem works perfectly for every number with 2 or less factors.
    Also, 5^4-5=620 and 2^5-2=30. Is that the significance of those amounts of money?

  • @314rft
    @314rft 9 лет назад +21

    $620. That obviously was raised from $30 due to inflation.

  • @metleon
    @metleon 10 лет назад +1

    First bagels now ice cream. This channel's making me hungry.

  • @heoTheo
    @heoTheo 10 лет назад +2

    Really this makes me so happy how joyful he is about math. Sometimes I get stuck on something, and then I get it. and then the best part comes I get to explain it in the same joyful manner. :D Great!

  • @arkanon8661
    @arkanon8661 5 лет назад +1

    "the first carmichael number 561"
    1 is carmichael, right?
    i mean, its not prime (which im pretty sure is the meaning of composite), and it passes 1^1-1=0 (which is divisible by 1)
    and it passed all tests up to its value there look

  • @jeffreylevyhe-him1959
    @jeffreylevyhe-him1959 10 лет назад +4

    Thanks for another wonderful video! It raises a couple of questions for me that I'm hoping you or a commenter can answer.
    1) Why does the test stop at p? For example, if you're testing whether 5 is prime, why isn't it of interest whether 6^5-6 is divisible by 5? I'm sure there's something simple I'm missing.
    2) The Wikipedia article on Carmichael numbers uses a different formulation: a Carmichael number is a composite n such that b^n = b (mod n) for 1

    • @andreasl3974
      @andreasl3974 3 года назад +2

      And here I am the 1st person who liked your comment 7 years later.

    • @filipheller
      @filipheller 3 года назад +1

      @@andreasl3974 youre not alone😉

  • @morganabbotts
    @morganabbotts 10 лет назад +1

    I love this channel so fascinating, helps with our in class debates for my A-level.

  • @FlyingTurtleLP
    @FlyingTurtleLP 10 лет назад +45

    620$? ... why not 561, 1105 or 1729$?

    • @rangedfighter
      @rangedfighter 10 лет назад +13

      maybe after taxes it's 561$ :P

  • @pafnutiytheartist
    @pafnutiytheartist Год назад +4

    This is probably one of the hardest ways to earn $600

  • @aoshi1992
    @aoshi1992 10 лет назад +17

    No disrespect for the other people that show in this youtube channel, but james is the best (and I just found out he have another channel now I have hours of videos to see =D)

  • @RobbieSherman
    @RobbieSherman 10 лет назад +19

    Thumbs up for the choc ice

  • @Devilyaki
    @Devilyaki 10 лет назад +24

    I have the number, just holding out for more icecream treats :3

  • @westforduk
    @westforduk 10 лет назад

    Thank you for bringing closed captions back, i've missed Numberphile!

  • @venkateshbabu1504
    @venkateshbabu1504 4 года назад

    If G gravitational constant is a derived entity of frequency division. When you divide frequencies you get gravity. But when you multiply you get energy. Any number raised to prime minus one can be a multiple of that number. G is the multiplier numbers of prime powers. If you have prime powers they always tend to create frequencies. Example 2 power 2 is four and you can always balance them.

  • @michaelempeigne3519
    @michaelempeigne3519 3 года назад

    if a number , n , can be factored into a * b * c * ........ then it is a carmichael number if ( a - 1 ), ( b - 1 ), ( c - 1 ), etc. divides ( n - 1 )
    so for 561 = 3 * 11 * 17
    ( 3 - 1 ) divides ( 561 - 1 )
    ( 11 - 1 ) divides ( 561 - 1 )
    and ( 17 - 1 ) divides ( 561 - 1 )

  • @GoingNoah
    @GoingNoah 11 месяцев назад +1

    You have to do this again with or about Daniel Larson's new proof on carmichael numbers.

  • @1KevinsFamousChili1
    @1KevinsFamousChili1 10 лет назад +2

    Whenever I hear Fermat I always picture Andrew Wiles, It threw me off when the painting of Fermat came up :P

  • @mindstormmaster
    @mindstormmaster 10 лет назад +4

    561^561 - 561 is surely divisible by 561 too right?

  • @valor36az
    @valor36az 10 лет назад

    Best explanation of Fermat's little theorem and application.

  • @gabriel-et3gy
    @gabriel-et3gy 3 года назад +1

    Just in case someone is wondering:
    2^341 - 2 = 4479489484355608421114884561136888556243290994469299069799978201927583742360321890761754986543214231550
    and thats equal to
    13136332798696798888899954724741608669335164206654835981818117894215788100763407304286671514789484550 * 341

  • @GeorgeDeLaRosa182
    @GeorgeDeLaRosa182 10 лет назад +189

    i live in california and it is 5:22 right now and i just woke up. my mother walks in my room and yells YOU ARE STILL UP? HAVE YOU BEEN WATCHING PORN ALL NIGHT? and i reply with no mother im actually watching a video on fermat's 'little' theorem. now im punished for 2 weeks. thanks math

    • @aidaneglin781
      @aidaneglin781 7 лет назад +22

      yep that totally happened...

    • @lyeahthatl6690
      @lyeahthatl6690 7 лет назад

      George G what does it mean?

    • @teekenny2965
      @teekenny2965 7 лет назад +1

      wait why did you get punished
      what does your mom have against maths videos

  • @velocity173
    @velocity173 8 лет назад +2

    I love your videos and cool prime tests, keep making great videos! Also do a video on the number 73 the best number

  • @radusavu2007
    @radusavu2007 8 лет назад +1

    3:12 2 ^ 341 ends in 2 ( 2 ^ 4k+1 ) . By substracting 2 we'll get a number who ends in 0 which divides to 5 . Also 3 ^341 ends in 3 ,substracting 4 we'll get again a number which divides to 5 . So Why doi you call 2 ^ 341 fermat liar and the other not ? Interesting theoreme .Thanks for sharing .

  • @Carvin0
    @Carvin0 5 лет назад +1

    I'm afraid James has made an error. Carmichael numbers pass the Fermat Little Theorem (FLT) for all integers less than the Carmichael number that are RELATIVELY PRIME to the Carmichael number, NOT ALL INTEGERS as indicated at 4:00. For example, 406 ^ 560 = 1 mod 561, but 407 ^ 560 = 154 mod 561. Notice that 561 = 3 x 11 x 17, 406 = 2 x 7 x 29, and 407 = 11 x 37. Notice that 406 has no factor in common with 561, that is, 407 is relatively prime to 561. There are 240 integers (none have 3, 11, or 17 as a factor) less than 561 that correctly "witness" 561 as a composite, and 319 "liars" that falsely suggest that 561 is prime. If EVERY integer a < p satisfies a ^(p-1) = 1 mod p, then p is truly a prime. But of course is is highly compute intensive to check that, so it isn't a practical test.

  • @mattlm64
    @mattlm64 10 лет назад +1

    I vaguely remember Fermat's little theorem being used to re-arrange some equations for RSA cryptography. A video on that would be nice as it's quite interesting, but might be quite difficult to follow for some people.

  • @gooser41
    @gooser41 10 лет назад

    Factual error: There are 21853 Fermat pseudoprimes for base 2. The number quoted in the video is missing the digit 5 and thus underestimating by one order of magnitude (and just for reference, there are 2163 Carmichaels below 25*10^9).

  • @enceladus32
    @enceladus32 7 лет назад

    James is my favourite person on this channel

  • @timchorle
    @timchorle 10 лет назад

    So can you do a video explaining why Fermat's little theorem should work? I'm sure their are various proofs of course, but I'm trying to wrap my mind around why this should logically work in the first place.. it seems a bit strange and amazing! Love the show keep up the great work!

  • @YouTodayKing
    @YouTodayKing 10 лет назад

    Yes! Dr. James Grime should do a lot more of these vids!

  • @zanti4132
    @zanti4132 5 лет назад

    2^341 - 2 = 2 * (2^340 - 1) = 2 * (2^10 - 1) * (2^330 + 2^320 + 2^310 + ... + 2^10 + 1). So, 2^10 - 1 = 1023 is a factor of 2^341 - 2. Since 1023 = 3 * 341, we see that 341 is a factor of 2^341 - 2 without having to calculate 2^341.

  • @malcolmclarke621
    @malcolmclarke621 9 лет назад

    Slow but flawless way to test for primes: talk the mod of all the numbers greater than 1 and less than n, which is the number you're testing to be prime. If any of the numbers >1

    • @RadicalCaveman
      @RadicalCaveman 8 лет назад

      +Malcolm-Lyndon Clarke Actually, you can make it shorter than that. You only need to use divisors that are prime themselves, and you only need to go up to the square root of n. So, for example, 97 is prime because it doesn't divide evenly by 2, 3, 5, or 7, and the next prime, 11, is already more than the square root of 97.

  • @smergthedargon8974
    @smergthedargon8974 5 лет назад +1

    The Russian guy (bad with names, can't remember) is my favorite professor on the channel, but Primes Grimes is an extremely close second.

  • @coelloello
    @coelloello 7 лет назад

    I dunno why but the choc ice bit completely slayed me, my jaw hurts

  • @carmacksanderson3937
    @carmacksanderson3937 6 месяцев назад

    To my understanding the $620 offer applies to something referred to as the PSW conjecture (as stated on John Selfridge's Wikipedia page)
    If a p mod 10 = ±3
    And 2^(p-1) mod p = 1
    And f_(p+1) mod p = 0, where f_n refers to the nth Fibonacci number
    Then p is prime (or so the conjecture goes). I myself have check every such number below 30 billion and found no counterexamples

  • @Descenacre
    @Descenacre 7 лет назад +1

    I was like "wait 341 isnt a prime, its divisible by 11 because the hundreds plus the ones equals the tens"(i like to check if numbers are divisible by 11 or 3)

  • @brunileshi
    @brunileshi 8 лет назад

    Small mistake: Carmichael numbers are odd composite numbers p for which a^{p-1} == 1 mod p for all a with gcd(p,a) = 1. If d | p, then d^c mod p can never be 1 for any power c.

  • @Mattio_
    @Mattio_ 10 лет назад +9

    Damn, I want a choc-ice everyday for the next few years!

  • @habibaghasafari2237
    @habibaghasafari2237 10 лет назад +1

    an interesting test for primes. i didn't know this. thanks brady

  • @TremaineMcCants
    @TremaineMcCants 10 лет назад +12

    Perfect

  • @TNR2K
    @TNR2K 10 лет назад

    +Alpha Craft
    The definition of a prime number is that it is only divisible by 1 and itself and no other numbers. So they are "prime".

  • @PaulDve
    @PaulDve 10 лет назад +4

    If you like this guy James he also has his own channel (singingbanana) that's just as interesting.

  • @ghassenmez7810
    @ghassenmez7810 10 лет назад

    if you want to chick if a number is prime , it would be much easier to use the definition:
    (n is prime) equivalent to ((n/m) is not a natural number 1

  • @benoitst-jean7295
    @benoitst-jean7295 5 лет назад

    Are there any stats on number n > k telling us statistically indicating the "efficiency" of this method?

  • @brunohoffmannfreire5317
    @brunohoffmannfreire5317 4 года назад +1

    U$ 620 is a huge amount of money, don't take it for granted.

  • @dunx125
    @dunx125 10 лет назад +6

    aww, whose the cutest little theowum in the world; you are little theowum, you are!

  • @kdryden29
    @kdryden29 10 лет назад

    I missed him! Nice to see him again!

  • @ItsTeezoUBZ
    @ItsTeezoUBZ 10 лет назад

    Bradah you make Math hella fun and interesting. LEGIT!

  • @Mechanikatt
    @Mechanikatt 10 лет назад +2

    From the definition, wouldn't 1 also be a Carmichael number? Every number minus itself equals 0, which is divisble by 1 :P

  • @postbodzapism
    @postbodzapism 10 лет назад +8

    Why do you have to impose the restriction 1p as each a is congruent to some a' mod p where a' is between 1 and p inclusive...

    • @vasilivanich3842
      @vasilivanich3842 10 лет назад +4

      If it works for all a < p (and obviously for p), then it works for all numbers, as any number 'c' can then be represented as c = (p + b), where b < p (or if c is big enough you just take some integer amount of p instead: c = (kp +b) - it doesn't really matter). What you then have to check is whether (p + b)^p - (p + b) is divisible by p, but all the summands in (p + b)^p when you multiply it by itself p times will contain p to some power exept for one, which is b^p. So you will have a bunch of numbers that are (p to some power)*(b to some power), but these are naturally divisible by p, and the only questionable thing left is b^p, but b is less than p and by assumption any number less than p satisfies the desired property, that is: b^p - b can be divided by p.

    • @Djorgal
      @Djorgal 10 лет назад +3

      Yes that's exactly that. Doing the test with a is the same thing as doing the test with a' its class mod p. If a number passes the test for all a between 1 and p then it passes it for all a.

    • @DiaStarvy
      @DiaStarvy 10 лет назад

      You don't obtain more information.
      Let's say a^p - a ≡ 0 (mod p), where 0

  • @thegettokidZz
    @thegettokidZz 3 года назад +1

    620 DOLLARS.
    I'M GOING TO WORK STRAIGHT AWAY

  • @shrimpbisque
    @shrimpbisque 6 лет назад

    It's funny the example he uses at first is 561, because you can tell at a glance that it's not prime; its digits add up to a multiple of 3, so it's a multiple of 3.

  • @newperve
    @newperve 6 лет назад

    This is one reason that you shouldn't necessarily trust what numbers tell you. The other is that some of them, while not actually liars are completely irrational.

  • @jontorstrm8714
    @jontorstrm8714 9 лет назад

    never been a math nerd but i´m starting to like this.

  • @NeutronicBusch
    @NeutronicBusch 10 лет назад +2

    KEEP DOING YOUR GREAT WORK!

  • @David-ud9ju
    @David-ud9ju 7 лет назад

    I love how he was contemplating spending the prize money on choc ices.

  • @shawnzhang6736
    @shawnzhang6736 10 лет назад +9

    1:29 Fermat did not prove this theorem, Euler did. Fermat merely stated it.

    • @leadnitrate2194
      @leadnitrate2194 5 лет назад +5

      Euler proved pretty much everything though. So just give some credit to Fermat, Euler gets more than enough as is.

    • @leadnitrate2194
      @leadnitrate2194 5 лет назад

      Sebasfort yeah I get your point. Didn't really think while I was posting. 👍

  • @DragonRider3879
    @DragonRider3879 5 лет назад

    1790, 1798, 1806, 1814, 1822, 1830, 1838, 1846, 1854, 1862
    Numbers can work with ^5
    Just so you know

  • @slomotrainwreck
    @slomotrainwreck 10 лет назад

    I, and many other "geeks" use Prime95 to stress-test the CPU & RAM in new computer builds.
    Very interesting video! Thumbs up!

  • @aaronbernal3189
    @aaronbernal3189 10 лет назад

    This is important to public key cryptography....you should do a video about that on computerphile!

  • @Ruaille
    @Ruaille 10 лет назад +13

    That darn three. Noone likes a snitch.

  • @PiotrBaczek87
    @PiotrBaczek87 10 лет назад

    Can you do a follow-up on how Carmicheal numbers affect RSA Cryptography and what primality test is used in RSA?

  • @Kapomafioso
    @Kapomafioso 7 лет назад +1

    I lost it at 2:50 "Fermat Liar uuuuuuuu" :D

  • @andrewbloom7694
    @andrewbloom7694 2 года назад +1

    When you've watched so many math videos on youtube you already know what Liar numbers are lol

  • @CaseyShontz
    @CaseyShontz 7 лет назад

    3:36 does anyone else here watch the show Chuck?
    Cuz in chuck, there’s a guy named Chuck (duh) and he’s a spy, and his cover name is Charles Carmichael. I thought that was interesting because “Charles Carmichael” was lying about his name and Carmichael numbers were lying about being primes.

  • @fionamarshall5465
    @fionamarshall5465 10 лет назад

    I love that 101101 is a Carmichael number and a palindrome.

  • @kyoung21b
    @kyoung21b 10 лет назад +3

    How are the Carmichael numbers distributed (e.g. do they get less dense as the values increase ?) ?

    • @PoweDiePie
      @PoweDiePie 7 лет назад

      They are less common than primes; but I don't know otherwise :/

    • @pakigya
      @pakigya 7 лет назад

      Karl Young yes they do which is why they are called pseudo primes.

  • @cmcqueen1975
    @cmcqueen1975 8 лет назад +4

    The prize shouldn't be $620, it should be $561.

    • @LazaroCarvalhaes
      @LazaroCarvalhaes 7 лет назад +2

      Tell'em that when you win. (rudeness uninteded)

    • @ragnkja
      @ragnkja 4 года назад

      No increase it to $1105

  • @igesio
    @igesio 10 лет назад +1

    I love Dr Grime

  • @manueldelrio7147
    @manueldelrio7147 7 лет назад

    the choc-ice a day thing is really tempting...

  • @RexGanymede
    @RexGanymede 6 лет назад

    james's sense of Irony/Satire enraptures me, substantially.
    *Ssss, **_oooooooo_* - indeed, Mr. Grime; *Ssss, **_oooooooo_* - indeed.