What does a ≡ b (mod n) mean? Basic Modular Arithmetic, Congruence

Поділитися
Вставка
  • Опубліковано 1 жов 2024

КОМЕНТАРІ • 424

  • @blackpenredpen
    @blackpenredpen  6 років тому +354

    What donuts are those?

  • @v-neko8074
    @v-neko8074 3 роки тому +116

    Some teachers in universities: 2h lecture
    blacklenredpen: 6minutes

    • @davidbrisbane7206
      @davidbrisbane7206 3 роки тому +2

      Too right mate, plus we can repay bprp's videos as often as we like.

    • @mohammedhussain6749
      @mohammedhussain6749 3 роки тому +3

      He is just explaining the procedure not the theory, origins or proof

    • @EulerJr_
      @EulerJr_ 3 роки тому +1

      @@aymenchamia7470
      I do, and he is 100% right.
      Our lecturer is extremely smart and knowledgeable no doubt, but he just can’t explain the procedures and concepts in a simple enough way for anyone to understand.

  • @bakirhaljevac3584
    @bakirhaljevac3584 4 роки тому +514

    It took you around 3 minutes to say what I needed to know, the same thing that my professor unsuccessfully tried to explain in one hour. Thank you so much

    • @v-neko8074
      @v-neko8074 3 роки тому

      same

    • @tristanfan4741
      @tristanfan4741 3 роки тому +8

      so fucking dmn right

    • @finghinmccarthy5021
      @finghinmccarthy5021 2 роки тому

      True

    • @JuuzouRCS
      @JuuzouRCS 2 роки тому

      True. I am right now going through the same experience.

    • @shreyas_._
      @shreyas_._ 2 роки тому +2

      I wonder which professor took one hour for congruence 😅then for sure your whole syllabus time schedule gonna wasted..., ഒരു മയത്തിൽ ഒക്കെ ആവം കേട്ടോ ...

  • @arnasvaicekauskas7693
    @arnasvaicekauskas7693 6 років тому +447

    Why is this video 2Pi minutes long ?

  • @johnlara1365
    @johnlara1365 4 роки тому +136

    I am a senior math and CS major, I have used modulo almost as much as I’ve used pi and I have always been confused by congruency. No one has been able to explain congruency more clearly and digestible than you. Thank you!

    • @dominicellis1867
      @dominicellis1867 Рік тому +6

      Basically you throw out the quotient and keep the remainder. It's periodic math like the roots of a trig function.

  • @sergioh5515
    @sergioh5515 6 років тому +172

    PLEASE MORE MODULAR ARITHMETIC! You're the best

  • @rainyday4709
    @rainyday4709 2 роки тому +13

    30min trying to understand this congruence with my book .
    And this man make me understand it just in 1:46 seconds
    I wanna cry .
    Why professor make life complicated whyyy ...
    THANK YOU SO MUCH.
    I really respect you 🙏🙏

  • @WSUFan2017
    @WSUFan2017 6 років тому +49

    You should do more number theory, especially stuff like Euler’s totient function (since it’s my favorite subject ;D)!

    • @blackpenredpen
      @blackpenredpen  6 років тому +4

      I will. In the meantime, you can check out Max's videos here: ua-cam.com/channels/P-ZCMz7olJPUI78b_bQrvQ.htmlvideos?disable_polymer=1

  • @MathForLife
    @MathForLife 6 років тому +78

    Ahah, "killing all math":DDD

    • @blackpenredpen
      @blackpenredpen  6 років тому +3

      Eightc yup!!!!

    • @blackpenredpen
      @blackpenredpen  6 років тому +5

      And max, you can record an intro and send it to me via google drive so I can put it in my videos to let more ppl know about ur channel.

    • @MathForLife
      @MathForLife 6 років тому +3

      blackpenredpen thanks!!

  • @GraceJoe-u6y
    @GraceJoe-u6y 5 місяців тому +6

    I watch 7 videos of about 20 minutes about modular arithmetic and didn’t understand anything but your 6 minutes video made me understand. I don’t know what to say

  • @Jack-cm5ch
    @Jack-cm5ch 6 років тому +49

    Omg saving my grade once again. God bless you. Wish you had a patreon...

    • @Wannabesage336
      @Wannabesage336 5 років тому +7

      For those of you watching this in the future:
      He does!
      www.patreon.com/blackpenredpen

  • @azure3544
    @azure3544 5 років тому +5

    I learned more from this guy than from my entire math class xDDD
    My math teacher made this look like rocket science...

  • @billofrights5064
    @billofrights5064 6 років тому +71

    When I took abstract algebra, I found
    a ≡ b (mod n) quite confusing. The meaning seems to be
    a (mod n) = b (mod n), but equivalence must mean more than this.

  • @Phelly2
    @Phelly2 5 років тому +21

    What the heck are you holding? A microphone? It looks like a psionic amplifier from the game System Shock 2. lol

  • @meccamiles7816
    @meccamiles7816 5 років тому +16

    Your ability to change the marker you’re writing with so fast is amazing...

    • @krimzonghost1987
      @krimzonghost1987 3 роки тому +1

      I read this comment and watched the video again just because of this. lmao. Wow! You were not joking.

  • @azharuddin7013
    @azharuddin7013 2 роки тому +2

    @blackpenredpen Hi,
    when you say that 10 is congruent to 2 mod(4) but that cannot be according to the first definition because 10 and 2 doesn't have same remainders.Plz help

    • @gototcm
      @gototcm 2 роки тому

      Actually, they do. 10 divided by 4 is 2 with a remainder of 2. 2 divided by 4 is zero with a remainder of 2. Hope this helps.

  • @navster100
    @navster100 4 роки тому +6

    im doing proofs with modular congruence and my head is exploding

  • @GreeeenT
    @GreeeenT 6 років тому +15

    do you have my schedule or something ?? how do you always upload what I need. thanks man !

  • @AlgyCuber
    @AlgyCuber 6 років тому +29

    H times i factorial

  • @scandalff4602
    @scandalff4602 4 роки тому +2

    How a and b have same remainder ?(at 0:55)

  • @zhangruoran
    @zhangruoran 5 років тому +10

    : D this is exactly what I taught my students.

  • @liamcauquil6800
    @liamcauquil6800 5 років тому +7

    Hey, good video! Could you explain how 10 ≡ -2 became 10 ≡ 2 by adding 4 to the -2?

    • @liitutereuiui4687
      @liitutereuiui4687 3 роки тому +1

      I also want to know

    • @Nour_Ayasrah
      @Nour_Ayasrah 3 роки тому +4

      too late, but if by any chance someone needs it later on, this is one way to think about it.
      note that if you are dealing with mod(n), any integer will be congruent to the set starting from 0 to n-1(i.e: {0,1,2,...,n-1}), so for mod(4) we have {0,1,2,3}, so now what happens if we add "4" or multiples of it to any of these? well, u go a full cycle/s so 0+4 = 0 mod(4), 1 + 2*4 = 1 mod(4) etc.
      so essentially inside the realm of mod(4) adding 4 is analogous to adding 0 in the normal arithmetic, does not change a thing. so -2 mod(4) = -2+4 mod(4) = 2 mod(4).

    • @azharuddin7013
      @azharuddin7013 2 роки тому

      @@Nour_Ayasrah when he says that 10 is congruent to 2 mod(4) but that cannot be according to the first definition because 10 and 2 does'nt have same remainders.Plz help

    • @Nour_Ayasrah
      @Nour_Ayasrah 2 роки тому +5

      @@azharuddin7013 hey buddy, the first definition says that both numbers have the same remainder when divided by n, and that is true here.
      2/4 = 0*4 + 2(this 2 here is the remainder)
      10/4 = 2*4 + 2(again this is the remainder)
      since in both cases the remainder is 2, they are congruent

  • @roof310
    @roof310 Рік тому +4

    (by wikipaedia) Actually, the first claim is the most correct one, same remainder when a and b are divided by n,
    a = kn + r, b = jn + r then we have a - b = (k-j)n + 0 which means that n | a - b (the last claim). If we add b to both side,
    a = Kn + b by setting K = k - j.
    edit: depends on variables to choose the most suitable one.

  • @KingofArmageddon20
    @KingofArmageddon20 4 роки тому +1

    So confused someone help! For 1) he says remainder is 2 and for 2) he says k=-1 which is the real answer

  • @UnathiGX
    @UnathiGX 6 років тому +6

    This is by far the best explanation....IMO!...here I come....!!!!

  • @WhiteDotX
    @WhiteDotX 6 років тому +21

    I just keeping learning a lot from you.
    Greetings from Mexico!
    Can you talk about set theory or keep doing number theory?

    • @blackpenredpen
      @blackpenredpen  6 років тому +2

      Silvestre Frijol Cruz thank you!! I will focus on number theory, probability and combinatorics and calc.

  • @ultrio325
    @ultrio325 3 роки тому +1

    *laughs in blue pen and green pen*

  • @jgja1931
    @jgja1931 2 роки тому +1

    Are you a singaporean?

  • @zellpeppers8181
    @zellpeppers8181 Рік тому +1

    thankyou so much!! this really helped a lot 🥰🥰

  • @barence321
    @barence321 2 роки тому +3

    In Beachy 4th Ed., the authors write " a ≡ b (mod n) if and only if n|(a - b)." The proof goes in both directions, so you see that n|(a -b) does indeed show that a/n and b/n have the same remainder. I just finished going over this proof again for my abstract algebra class. Very simple when you do the proof both ways.

  • @michelle732mn
    @michelle732mn 2 роки тому +1

    THANK YOUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU!
    P.S. I laughed when you said mod 1 kills all the math lol

  • @xampzie4995
    @xampzie4995 2 роки тому +1

    I’m in knowledge bowl and this gave me a hard time

  • @giantdad7
    @giantdad7 6 років тому +4

    Please keep uploading Number Theory videos!

  • @crisronaldo934
    @crisronaldo934 5 років тому +1

    1)PROBLEMA NIVEL UNI:
    TEMA: DIVISIBILIDAD
    a1b2c3d4=13°
    a2b3c4d^a2c=13°+3
    a3c=7°+5
    a2c --> mínimo
    calcule a+c
    2)Calcule el residuo de dividir E entre 25
    E=24^95 +24^94 .7+24^93 .7^2+24^92 .7^3+......+24.7^94 +7^95
    3)halle el valor de "a":
    ( aa(b+3)3(a+1)4₁₈ ^aa(a+1) ^ (a-1)aa₅ ) -a =9°
    4) nnmmnnmm....nnmm₇=......p3₅
    ....
    calcule el máximo valor de x en:
    mpnnpm₁₂=.......x₇
    4) ARITMÉTICA-MÚLTIPLOS
    halle el máximo valor de d.c si se sabe que:
    2abba^(b!-a!) =11°+9 ademas: (b-5)a3cd5=99°+33

  • @bgbg418
    @bgbg418 3 роки тому +1

    Wow I wish I found this in my first year. It would've saved me hours of lengthy abstract examples and confusion. Why do universities make things so unnecessarily complicated sometimes 🙄.

  • @ananyanoronha632
    @ananyanoronha632 4 роки тому +1

    If n=1,a should be = to b right??
    *kills all math*

  • @sammurphy8089
    @sammurphy8089 5 років тому +3

    very nice movie from Japan!

  • @juandelacruz9125
    @juandelacruz9125 6 років тому +3

    Thanks blackpenredpen for teaching us this!

  • @pedrosso0
    @pedrosso0 3 роки тому +1

    "Do not do mod1" me: does mod 1
    x(mod 1)=sawtooth[x]
    TimE FOR COMPLEX MODS!

  • @nithin8432
    @nithin8432 2 роки тому +4

    just had a great and clear understanding this was the lecture i needed thanks a lot mate!!!

  • @areebcopycat6765
    @areebcopycat6765 2 роки тому +1

    Basic? Basic! yeah right - |: |:

  • @abuhanifhanif3636
    @abuhanifhanif3636 4 роки тому +1

    Thanks a lot from Bangladesh

  • @jihyepark9139
    @jihyepark9139 4 роки тому +1

    Our major instructor discussed this topic like using speed of light.... Boom finish!!

  • @aayushve426
    @aayushve426 5 місяців тому +1

    Great video as always !

  • @ayyagarisrinivas5082
    @ayyagarisrinivas5082 4 роки тому +1

    Helpful man thanks ; )

  • @shreenidhhi8633
    @shreenidhhi8633 4 роки тому +1

    I have a doubt.
    From a=(k×n)+b
    Can we say this is similar to
    dividend =divisor × quotient +remainder

  • @BentHestad
    @BentHestad 3 роки тому +2

    Very helpful! Thanks!!

  • @militantpacifist4087
    @militantpacifist4087 2 роки тому +1

    This video has the most epic donut-math intro to be honest.

  • @PPV_911
    @PPV_911 4 роки тому

    كتبت كذا شجضنيريكثنرثكلهبنب وطلع لي هذا الفيديو 😂

  • @frankensteinapps9442
    @frankensteinapps9442 Рік тому +1

    Thanks man I was bit confused in equivalence relations when this came up , turns out I was interpreting it in a wrong way

  • @Surya_Kiran_K
    @Surya_Kiran_K Рік тому +1

    I would attend every class of this guy 😭👍💓

  • @danieljohannbutcher9927
    @danieljohannbutcher9927 4 роки тому +1

    The black ball looks like a prop from the movie parallel. Great explanation, weird microphone.

  • @itzmrinyy7484
    @itzmrinyy7484 3 місяці тому

    Thank you so mucj for this video! I was just watching an IMO prpblem solving video and i couldn't help but wonder what "mod(n)" meant.

  • @sunitanath3160
    @sunitanath3160 4 роки тому +1

    OMG.. this vedio is about 2π min. Long

  • @bengper8044
    @bengper8044 3 роки тому

    How could you formulate into words the question 28x ≡ 124 (mod 116)?
    I have a hard time getting my head round what it means...

  • @ZectonplaysMC
    @ZectonplaysMC 5 років тому +1

    Dude i normally watch ur vids for fun but now i actually need help and i come back to ur channel😂

  • @TheAlison1456
    @TheAlison1456 2 роки тому

    In 10 cong 14 (mod 4)-->10=k*4+14, why is k=-1?
    I understand that practically 10=(-1*4)+14-->10=-4+14-->10=10, and this seems to be via Substituion, but it also seems arbitrary.
    That's ambiguous, unlike operating a number to both sides of an equation.

  • @Amine-gz7gq
    @Amine-gz7gq 2 місяці тому

    A 4:28, you haven't convinced me : 10 and -2 when divided by 4 don't have the same remainder (you get 2 for 10 and -2 for -2).

  • @lizzieaoi7140
    @lizzieaoi7140 3 роки тому

    blacklenredpen:"mod 1 kills everything, don't do that"
    me:Wait why? lemme think, 3 mod 1 is.. oh is 0, ok, and 4 mod 1 is... Oh... I get it...

  • @ghassanabdalsalam9938
    @ghassanabdalsalam9938 2 роки тому +1

    thaaaaaaaaaaaaank you , amazing , I love your explanation

  • @krimzonghost1987
    @krimzonghost1987 3 роки тому +1

    C# exercises led me here... and I ain't even mad. Awesome video!

  • @yon1623
    @yon1623 Рік тому +1

    I spent an hour trying to understand it from my book... 6 minute video is what i needed.

  • @madhurimamohanty2867
    @madhurimamohanty2867 3 роки тому +1

    Well in India there's an exam called NMTC where you have to learn this as a part of syllabus when you're in grade 6. By the way I'm of grade 6 and I enjoy watching your calculus lectures

  • @zstar8397
    @zstar8397 Рік тому

    Hey hope you are doing alright just I wanna say that
    GOD loved the world so much he sent his only begotten
    son Jesus to die a brutal death for us so that we can have eternal life and we can all accept this amazing gift this by simply trusting in Jesus, confessing that GOD raised him from the dead, turning away from your sins and forming a relationship with GOD. :)

  • @Paul-im7pd
    @Paul-im7pd 4 місяці тому

    Can you show why 6^n always ends with 6 for natural n>0 with this theorem? Trying with that but can't really show it. I tried induction but not sure how induction works with congruence.

  • @nirmaljyotieducationclasse9965
    @nirmaljyotieducationclasse9965 4 місяці тому

    hey man how did you derive the 2 equation i am having a lot of trouble understanding that . how did you remove mod from the equvalence and all that

  • @ManuAyu255
    @ManuAyu255 3 роки тому +1

    Chinese ho Kya

  • @jasonshih3633
    @jasonshih3633 8 місяців тому

    Bro explained everything when my professor couldnt

  • @ryanziller220
    @ryanziller220 2 роки тому

    I can guarantee that most people will confuse the activity shown as comparable to developing a conceptual understanding of modular congruence. If he provided any sort of discovery in which one could find the relativity of discrete mathematics while performing the procedures of modular arithmetics then we could satisfy the looming problem of: When and where have I seen this before? Instead, as is the case of 'cutting corners', he stressed his strategic competency while disregarding the importance of the methodical alternatives represented. Those people whom hate maths or find the language nonsensical and deceptive do so because oftentimes someone who is still learning to teach the subject(s) denotes pertinent information yet fails to instruct on the basis of that which is the significance of an ontology; implying that, the concepts which are introduced can be conferred to the relevancy of an instantaneous appreciation by others. Per inference, everyone not exploring a career as a mathematician is ignoring the facts of exercises of the discipline. Why teach math while you are not becoming a mathematician?

  • @erickarbieto8111
    @erickarbieto8111 4 роки тому +1

    Eres un crack! Y todo lo digo en español, porque hasta en Latinoamerica disfrutamos de tus videos; en serio, aprendo muchísimo! Thank you!

  • @kems1592
    @kems1592 5 років тому

    I don't understand the third approach. What are we actually looking for?? Please answer thanks

  • @regenciaamiragracer.4524
    @regenciaamiragracer.4524 Рік тому

    I hope this comment will be noticed. Can b be greater than the value of n? Thank you in advance to the person who will answer✨✨

  • @skystar7350
    @skystar7350 3 роки тому

    in Viet Nam, I have learned a|b means a:b don't have any remainder. so it kindda make me confused when I read a English book have the notation a|b which is means b:a don't have any remainder.

  • @Isac986
    @Isac986 5 років тому +2

    Excelente me salvaste de leer mucha álgebra, continua con el álgebra moderna que es bien interesante al igual que el calculo

  • @xiaoyuchen7387
    @xiaoyuchen7387 2 роки тому

    I just wanna get a clean pause before the big damn THATSIT shows up

  • @eduyantra8048
    @eduyantra8048 5 місяців тому

    m² = m mod 1000
    What could be the values of m??

  • @psrs985
    @psrs985 2 роки тому +1

    Mom I'm becoming a mathematician

  • @Ethan-mj6wy
    @Ethan-mj6wy 6 років тому +3

    Great video, loving all the number theory :)

  • @sakeenabi9524
    @sakeenabi9524 2 роки тому

    Why don't you use coler mike ,don't your hand get hurt while taching and holding mike continuesly 🤔

  • @arminhakimi5758
    @arminhakimi5758 3 роки тому

    That’s so confusing ,this should be reported
    This is not mathematically right. The congruence of a is the remainder that we get by devision to n

  • @andrewkernan1028
    @andrewkernan1028 4 роки тому

    Why are you holding a bowling ball with a wire attached while using a marker and whiteboard...?

  • @roseantoinettepabalate6971
    @roseantoinettepabalate6971 4 роки тому

    How 10 / 4 = 2 remainder 2 happened?? it should be remainder 5

  • @sazsaiglesias
    @sazsaiglesias 2 роки тому

    you saved my exam tomorrow..thank you

  • @Amanupadhyay-po6ls
    @Amanupadhyay-po6ls 2 роки тому

    Great Explaination sir 👍
    11 grade student fom India

  • @rede_neural
    @rede_neural Рік тому

    Can I solve for i in this equation?
    (n-i) % (m+1) = 0

  • @pranavkumar1747
    @pranavkumar1747 3 роки тому

    How a nd b same remainder when divided by b???plzzz reply..

  • @motivationalcomred
    @motivationalcomred Рік тому

    summary: a = b mod m is known ads congrunce relation where a divides m and b divides m with same remainder and a is some constant times *m +b

  • @hamelillah7545
    @hamelillah7545 2 роки тому

    Hi;
    why/
    4 mod 5 = -1
    and
    -1 mod 5=4
    thanks

  • @bepo1873
    @bepo1873 3 роки тому

    That is a weird-looking microphone!

  • @sugog1923
    @sugog1923 8 місяців тому

    Can you make it clear about the -ve 2 part....😅

  • @avatarmh
    @avatarmh 4 роки тому

    This guy nailed it. However, you might like to think about congruence, blackpenredpen covered it. Clarifying and memorable. Now I can move onto some proofs that have been baffling me!

  • @atruety
    @atruety 4 роки тому

    I want more video about this please

  • @marnierogers3931
    @marnierogers3931 2 роки тому +1

    Great video, would love some more examples to cement how to use :)

  • @samyakmarathe3434
    @samyakmarathe3434 2 роки тому

    For programmers, it simply means: a%n==b%n

  • @michelangelina4790
    @michelangelina4790 5 років тому

    what if i have -660x ≡ 121mod143 how does that turn into 55 ≡ 121mod43 (the professor wrote -660 ≡ 55mod43 but i just cant wrap my head around if someone could please help i would be very grateful.... i have a very important exam coming up )
    i mean i understand why -660≡55mod143 and why then we go to 55≡121mod143 BUT HOW THE HELL WAS I SUPPOSED TO COME UP WITH THE NUMBER 55 thats my point what is the thought process behind getting to the replacement of -660 with 55 how did we come up with 55....??????

  • @NeO-bl2ux
    @NeO-bl2ux 3 роки тому

    I’m in grade 8 and learning about modular arithmetic what am I doing lol

  • @scar6073
    @scar6073 Рік тому

    Thank you for explaining this in a straightforward manner, I FUCKING LOVE YOU!

  • @soumyachandrakar9100
    @soumyachandrakar9100 6 років тому +2

    Aren't they tasty 🍩 Donut?

  • @masongkhun5292
    @masongkhun5292 5 років тому

    Hey bro ! Maybe I’m the latest one for this video but I want you to solve a math problem
    Here it is!
    Prove that: 1•3•5•...•2013+2•4•6•....•2014 is a multiple of 2015
    I hope you see my comment and solve it for me. Thank you !

  • @sohailasghar8684
    @sohailasghar8684 4 роки тому

    a=b mod 1
    Mathimatics end😎😎😎😎