Numbers 3 || Number Systems || CAT Preparation 2024 || Quantitative Aptitude

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  • Опубликовано: 6 фев 2019
  • Number System by Ravi Prakash | Quantitative Aptitude for CAT 2024
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Комментарии • 404

  • @nishanthhonna8406
    @nishanthhonna8406 3 года назад +231

    This is awesome sir . Helping so many poor students who cant afford coaching. Hats off to you sir

    • @experimentointerneto902
      @experimentointerneto902 3 года назад +4

      Can u tell the subtopic arrangement of watching number system.. Bcoz i think its mixed up

    • @GOKU-tt6zl
      @GOKU-tt6zl 3 года назад +3

      @@experimentointerneto902 it's not it's in order

    • @Someone7676
      @Someone7676 2 года назад +8

      Bhai hum toh coaching bhi jate h but vha inka 10% bhi ni pdhate .... time center m

    • @Harrystyles0004
      @Harrystyles0004 2 года назад +2

      @@Someone7676 sahi kahe bhai

    • @hetbhatt9441
      @hetbhatt9441 2 года назад +1

      What was your cat score

  • @shruti9557
    @shruti9557 2 года назад +25

    You just proved that legend do exist!.....BEST CHANNEL I'VE EVER COME ACROSS!....(kudos)

  • @hiraburney3123
    @hiraburney3123 3 года назад +62

    Thank you for this. You are providing help to so many non maths aspirants who even with coaching are unable to cope up. This is the best thing on the internet for me.

  • @amitsahu4782
    @amitsahu4782 2 года назад +18

    It’s really great to have u helping us in this way.arguably the best content I have ever had in RUclips for helping the aspirants for free.

  • @aayushikashyap_
    @aayushikashyap_ 8 месяцев назад +4

    Maine bhot sare classes kiye h no. System k...no.systm k nam sun k hi bore ho jati thi bt...apke jaisa kisi ne ni pdhya ...u r jst amezing sir... thanks to maa Durga jo apka channel mila❤️..lots of respect frm bihar😊

  • @vankaryash3142
    @vankaryash3142 3 года назад +11

    a^2 - b^2 = (a-b) (a+b)

  • @batulrizvi8390
    @batulrizvi8390 2 года назад +7

    Sir. HOW ARE YOU SO AMAZING!!! Thank you for this

  • @digvijaysingh1997
    @digvijaysingh1997 3 года назад +8

    1007 is not a prime number but 1007^2-1 is perfectly divisible by 24 and 1007 numeric digit sum is 8 i.e. not 3, 6 or 9, so we cannot find if a number is prime or not by these two methods. am I right???

  • @navreetkaur1215
    @navreetkaur1215 2 года назад +12

    The digital sum of 973 is 9+7+3=19
    19= 1+9=10
    10=1+0=1
    but '1' is neither prime nor composite.
    Does that mean the digital sum method cannot be applied on this question?

    • @zeenatkhan1575
      @zeenatkhan1575 4 месяца назад

      Op 😂😂

    • @Nilotpal_Chakravarty_
      @Nilotpal_Chakravarty_ Месяц назад +1

      it can be applied the digital sum of 973 is 1 which means it cannot be determined with the digital sum if it is prime or composite. Note, that the digital sum is like a negative test it guarantees that the number is not prime if the DS is 3,6,9 but when we get any other answer the primality of that number is undetermined.

  • @rhutvigawai5672
    @rhutvigawai5672 3 года назад +17

    Sir , thankyou so much for everything you have done students like us who can't afford coaching are blessed to have you.

    • @tusharrj6578
      @tusharrj6578 3 года назад +1

      In video at 17:35 I have query is 101 is prime number right...but sir telling 101 can't be prime number how? Can you tel me plz rhutvi

    • @yashmehrotra6201
      @yashmehrotra6201 2 года назад +3

      @@tusharrj6578No Tushar sir is not saying that 101 is not a prime number. He is saying that if we multiply 101 with the other factor it can't be prime anymore because then we will have 3 factors of 1000001 that are 1, 101, and 1000001. Therefore, 1000001 is a composite number.

  • @Ok12376
    @Ok12376 2 года назад +4

    a square + b square =
    ab+ab+1
    But this only applies.for square and not for every even exponent.

  • @TheDHemant
    @TheDHemant Год назад +2

    Sir, very nice. Theory explained @ video time 10 minutes in this video,:
    Can it be used to find factors of a composite number? I.e. to know if we have found all the factors and furthermore finding is not required?

  • @ahmedshaikh6053
    @ahmedshaikh6053 2 года назад +8

    Thank you so much sir for this awesome session❤️

  • @user-nd3wn1dq4z
    @user-nd3wn1dq4z Год назад +3

    Sir this is immense help I'm really grateful for this, as maths was something I was really afraid of I'm currently in class 11th , I don't have maths but I'm confident your lectures will lead me to the IIMs .
    Thank you!!

  • @sushantjha8373
    @sushantjha8373 5 лет назад +74

    Amazing video. This has to be arguably the best online content. The concepts taught and even the level of questions are terrific. Kudos sir !

    • @Rodha
      @Rodha  5 лет назад +21

      Thank you

    • @jibinjoby9523
      @jibinjoby9523 2 года назад

      Bro did u wrote cat exam

    • @zoro3188
      @zoro3188 2 года назад

      @@jibinjoby9523 yes I did

    • @AyushKumar-wl8cx
      @AyushKumar-wl8cx 2 года назад

      @@zoro3188 Coaching ya self study bro??

    • @hetbhatt9441
      @hetbhatt9441 2 года назад

      What was your cat score?????

  • @vijayaj9691
    @vijayaj9691 Год назад +8

    1000001 how it can be 10 to the power of 6 ? 10 to the power of 5 only gave100000 pls clarify my doubt ! .

    • @venkateshV-ss4lc
      @venkateshV-ss4lc 3 месяца назад +1

      10*10*10*10*10*10 = 1000000. You should aware of the zeros. 10 lakh has 6 zeros on it. 1 core has 7 zeros on it. Check for power table you will understand.

  • @shrutipandey3113
    @shrutipandey3113 11 месяцев назад

    1000001 = 10^6 + 1^6
    n is even. Hence, we can't conclude anything.
    But if we write it as (10^2)^3+(1)^3. This tells us that it is not a prime number. How will we know which power to consider?

  • @nikhithamk5865
    @nikhithamk5865 2 года назад +11

    Thankyou so much for these videos .
    I ' m a IIM aspirant who is not able to affort coaching classes.
    Your classes are really helpful for students like me.
    Where can we get the practice questions for these sessions?

  • @udaykiranuday1493
    @udaykiranuday1493 Год назад

    Sir, the question is 3^193+5. If we replace the no. 3 with 4 then how to determine the ans is prime or composite. Bcoz even + odd is odd.

  • @Sahibaamir
    @Sahibaamir 2 года назад

    Sir aapne (10²)³+1 mai cube 3 cut kia hai kya you factorise it in (10²+1). Plz tell

  • @TheDHemant
    @TheDHemant Год назад

    Sir @4 minutes of video time, will it be easier to start with the smallest prime number? I mean any reason why you are starting from the largest prime number?

  • @tanvigupta4842
    @tanvigupta4842 3 года назад

    Sir as you said digital sum of prime number be 3,6 or 9 with example 949876=9+4+9+8+7+6=43=4+3=7
    Here this is not a prime no then how digital sum will give prime no.? Plz explain

  • @LearnsomethingXYZ
    @LearnsomethingXYZ 8 месяцев назад

    From where we can practice the questions sir? Which biok will be better for CAT

  • @richasingh9621
    @richasingh9621 Год назад

    Which section should we look after this ?? Factors 1??

  • @blackhunter3757
    @blackhunter3757 4 года назад

    Sir all you ask is about small numbers like 36,54,68.. But what if they ask for larger numbers like 2379,3798,5577.plz reply sir

  • @aakritimittal4610
    @aakritimittal4610 4 года назад +2

    Sir...where can I get quizzes you were talking about the past years papers that you'll discuss?

  • @aminahamadkhan3766
    @aminahamadkhan3766 3 года назад +5

    i didnt get the logic for square root for finding its prime no. or not at time 7:51
    Any one up there who got the logic ???????????????????????????????????????

  • @harshmeanshappiness
    @harshmeanshappiness 4 года назад +2

    Your are doing a great job👍

  • @ujwalkachade3459
    @ujwalkachade3459 26 дней назад

    24:37 it is not always divisible , it is divisible by a+b only if n is odd...take a = 2 n = 2 b = 1, 5 is not divisible by 3

  • @brajmohanupadhyay1753
    @brajmohanupadhyay1753 3 года назад +2

    You say digit sum can never be 3 , 6 or 9. But in 973=9+7+3=19=1+9=10=1+0=1 so it's a prime no but it's not please explain sir

  • @ayushik8089
    @ayushik8089 3 года назад

    Sir which book should we refer for daily practice

  • @LOKABHIRAM
    @LOKABHIRAM 2 года назад

    Square root method may be time taking for 3 digits or more numbers. Is there anything else method

  • @donaldrook9359
    @donaldrook9359 Год назад +1

    Where can i practise question from this topic sir please reply 🙏🙏🙏🙏

  • @treasuretoyshop1674
    @treasuretoyshop1674 2 года назад

    if for a^odd - b^odd is 1 then it is prime or composite

  • @gunjanroy5704
    @gunjanroy5704 4 года назад +6

    Thank you sir, This series of videos is very helpful to me, easy to understand and probably the best online content

  • @poojab4967
    @poojab4967 4 года назад +11

    Amazing online content till date.You are just amazing.keep going sir.

    • @harshithaksubramanyam6135
      @harshithaksubramanyam6135 3 года назад +2

      hope you would have completed writing your cat . can i know how much did his videos help you

    • @abhinavsharma341
      @abhinavsharma341 3 года назад +1

      @@harshithaksubramanyam6135 pta lge toh meko bhi btana

    • @shivampruthi6833
      @shivampruthi6833 7 месяцев назад +1

      ​@@abhinavsharma341mujhe bhi bta do

  • @abhijeetsingh9084
    @abhijeetsingh9084 2 года назад +1

    Is there any video where this topic is continued

  • @abhishekgaikwad5485
    @abhishekgaikwad5485 2 года назад

    great videos very easily explained

  • @rakshitmittal6288
    @rakshitmittal6288 2 года назад +1

    Sir, Pdf notes are available of these videos.

  • @KhushiKumari-ll2ru
    @KhushiKumari-ll2ru 3 года назад +1

    At 10:40 .....A number that is not divisible by 2
    Can never be divisible by 6 ??
    How is it true??

  • @IshankChoudhary
    @IshankChoudhary 4 года назад +8

    Sir ratvao Mt p and C ki trah ni h ye video Jada questions nhi h bs concept hai pta ni lagra kaise apply honge different type of question mai

  • @darshanpatil7777
    @darshanpatil7777 2 года назад

    Sir, why a^2 + b^2 cannot be factorised?

  • @tiktokreel92
    @tiktokreel92 2 года назад +1

    By degital sum prime ni sum can never be 3,6,9 but 7498 sum is 28-10-1 (it is prime) but no 7498 is a prime no ????

  • @santhoshsivan6650
    @santhoshsivan6650 3 года назад

    i have a doubt in the last part like any number of the form a^n +b^n is divisible by (a+b) you said for example take 2^6 + 1^6 = 65 which is not divisble by 3 (i.e.a+b) why this happens then how can we apply this for all other questions of similar pattern

    • @rumourtales4997
      @rumourtales4997 3 года назад +2

      a^n+b^n is divisible by (a+b) only when 'n' is odd. When 'n' is even then it's can't be factorised.
      In your case 'n' is even (i.e., 6) , so its can't be factorised.

  • @sarthakpatra9261
    @sarthakpatra9261 Год назад +3

    as seen from the last example 973 is a composite number but it is satisfying the first 2 conditions at 11:15. I have a doubt here. Sir, can you please clarify this... Thank You

    • @catch_me_ifucan
      @catch_me_ifucan Год назад +3

      you need to check with all the 4 conditions.
      if all 4 conditions satisfy then its a prime number

  • @unnatisaxena2434
    @unnatisaxena2434 3 года назад +1

    And thank you so much sir...🙏
    You really taught well

  • @blackhunter3757
    @blackhunter3757 4 года назад +1

    Sir can you again explain divisibility part

  • @vinaymetri7706
    @vinaymetri7706 Год назад +9

    18:04
    Sir you have written a^2 - b^2 = (a-b)(a-b)
    Sir it should be (a+b) (a-b)

    • @maitrisinghai
      @maitrisinghai 5 месяцев назад

      bas ye hi comment dhoondh rahi thi

  • @yashaswinitg9299
    @yashaswinitg9299 2 года назад

    Thankyou so much sir 🙇
    I couldn't afford it for much price

  • @AashishKumar-km2bd
    @AashishKumar-km2bd 2 года назад

    How come psquare minus 1 is div by 24, sir plz explain

  • @pujaraj5908
    @pujaraj5908 3 месяца назад

    You're doing god's work

  • @user-tr6mp3ep8r
    @user-tr6mp3ep8r Год назад

    in the question of 1000001 a prime or not it can be represented as 6k-1 then why it is not prime

  • @1morerep491
    @1morerep491 3 года назад +1

    Please explain the last question

  • @gunvitsingh3371
    @gunvitsingh3371 2 года назад

    This All Vedioes will help in GATE SSC BANK EXAM ?

  • @officiallodhi3967
    @officiallodhi3967 3 года назад +1

    Better than unacademy ✌✌✌✌✌✌

  • @plato4180
    @plato4180 4 месяца назад

    Thank you so much sir!!

  • @harshthakkar6653
    @harshthakkar6653 4 года назад

    You are the best sir 💪

  • @omanohar12
    @omanohar12 3 года назад

    very helpful , thank you

  • @rishabgupta3419
    @rishabgupta3419 2 года назад

    Great explanation👍

  • @manju6480
    @manju6480 3 года назад

    Can anyone share a link of fundamental principles of counting in this comment pls

  • @vilegend9339
    @vilegend9339 9 месяцев назад

    Like this where can i get DILR and VARC

  • @ManuSrivastava_
    @ManuSrivastava_ 2 года назад

    Thank you so much sir.❤❤

  • @dineshbabu8831
    @dineshbabu8831 Год назад

    10:31 but why are we only checking divisibility of only prime factors....

  • @Aditya-ol8ev
    @Aditya-ol8ev Год назад

    How would you explain 1000001 is not a prime number. Please make me understand again sir

  • @sailaxmianumula7554
    @sailaxmianumula7554 Год назад

    Perfect session.....

  • @Harrystyles0004
    @Harrystyles0004 2 года назад +1

    Give a medal to this man

  • @spxtfxre1
    @spxtfxre1 2 года назад

    why does this channel not have 1mil subs??

  • @prajwalrao4514
    @prajwalrao4514 3 года назад

    Can someone explain me the P^2-1 / 24 method , also the first two ones. I did not get those. because 973^2 -1 is divisible by 24 but its not a prime number.

    • @kapilsarkar9223
      @kapilsarkar9223 3 года назад

      the reverse are not always true . like all prime numbers should be of the form 6k+/-1 , but all numbers having the form 6k+/-1 is not prime .

  • @cumulusmusic100
    @cumulusmusic100 9 месяцев назад

    Thank you Sir 🙏

  • @rajeevkumar-ti7zm
    @rajeevkumar-ti7zm 3 года назад

    but 973=6*162+1 so shouldn't it be prime

  • @sharayupatil1424
    @sharayupatil1424 4 года назад

    Thank you Sir

  • @ashutoshchaturvedi2797
    @ashutoshchaturvedi2797 2 года назад

    Can prime number be 3*2*k ± 1 = 3k ± 1 ??

  • @krishnaDas-gh4er
    @krishnaDas-gh4er 4 года назад

    Sir Last wale question mein jo number hai wo prime they ya composite aapne bataya nahi? Pls tell
    Thank you so much

  • @ironman2.026
    @ironman2.026 2 года назад

    1:00
    Given P ≠ 2 or 3

  • @karthikmadhusoodanan7274
    @karthikmadhusoodanan7274 3 года назад

    brilliant sir

  • @rohit49..92
    @rohit49..92 3 дня назад

    thankyou sir......

  • @gethingeorge4140
    @gethingeorge4140 2 года назад +3

    If A^n +B^n is divisible by A+B then what does it mean prime or not?

    • @AryanSingh-vi1oz
      @AryanSingh-vi1oz 2 года назад +3

      It means its not prime..
      Because uss number ka ek aur factor aa gya h and kisi bhi number ke 2 se jyada factor hote hein toh voh prime nhi composite number hota h

  • @durgamishra7994
    @durgamishra7994 10 месяцев назад +3

    Sir, the number 973 should be a prime number by the p2-1 divisibility by 24 rule, as 973 square minus one is completely divisible by 24. Kindly clear the doubt sir

  • @pradipto_de
    @pradipto_de Год назад

    in @16:48 why don't take digital sum?

  • @asthakanodia-6671
    @asthakanodia-6671 2 года назад

    Sir lcm aur hcf ke questions ni btae apne

  • @official.frostburn
    @official.frostburn Месяц назад

    Guys stick with the prime method where we find the square root of the number closest to the given number to find whether the number is prime or not. It's the most reliable method but lenthy.

  • @Tara-vh4yk
    @Tara-vh4yk 3 года назад

    am really bad at this can you let me know once we find its always divisible by 7 how does that answer whether it is prime or composite

    • @shriyanshtiwari2610
      @shriyanshtiwari2610 3 года назад +4

      if a no. is always divisible by 7 then it is a composite no. because it has more than 2 factors. for example take 14,we know that 14 is divisible by 7 and also 2 so it is a composite no. because it has more than 3 factors that are 1,2,7 and 14 itself.
      a prime no. has only 2 factors that is 1 and the prime no. itself For ex 7
      7 is only divisible by 1 and 7

  • @Live_lifestyle_09
    @Live_lifestyle_09 Год назад

    Can you sir explain me in the last one sum in the video why you wrote always divisible by 7??? From where the 7 was come pls if anyone know

    • @aarvi_bts_army_ot7406
      @aarvi_bts_army_ot7406 5 месяцев назад

      If you solve √973 then you get 31. Something and you can check (p

  • @piyushkumarsingh3439
    @piyushkumarsingh3439 Год назад +1

    Part 4 is missing sir

  • @bhavyalukka601
    @bhavyalukka601 Год назад +2

    Sir i have a doubt,
    1) On that question of 973 is prime or composte, can't we use that formula of digital sum can never be 3,6 or 9
    So 9+7+3 = 19, 1+9 = 10 , 1+0 = so 1, so therefore it is a prime number, but in the same way as you explained it is also divisible by 7 ...
    Please show me where I am wrong?

    • @swetachundawat6640
      @swetachundawat6640 9 месяцев назад +2

      If digital sum of any no. is 3, 6, or 9, then the number is definitely not prime, however, the its converse is not true that is if the digital sum of any no. is not 3,6, or 9, then the no. not necessarily be prime

    • @bhavyalukka601
      @bhavyalukka601 9 месяцев назад

      I forgot the number system and will have to revise again 😅 Thanks btw

  • @manjunathkalal987
    @manjunathkalal987 2 года назад +1

    Sir i am prepairing cat2023 this syllabus is ok

  • @hitarth1789
    @hitarth1789 Год назад

    3 is a prime number and the digital sum will be 3 is this not the case

  • @divyabhatia8677
    @divyabhatia8677 Год назад

    To check a prime number through digital sum, the condition is whether the sum shouldn't be 3, 6 or 9 or whether it shouldn't be divisible by 3,6 or 9?

    • @barshasaha1658
      @barshasaha1658 11 месяцев назад

      The sum is notequal to3 , 6 and 9 bcos in digital sum we check for the sum of digital sum so logically it also it is concludable

  • @gourigogoiofficial6513
    @gourigogoiofficial6513 Год назад

    Sir after the number system (3) , which part should I continue factorials or factor?

    • @user-nd3wn1dq4z
      @user-nd3wn1dq4z Год назад

      Factor I suppose is it true? Are you done with it
      If yes may you please guide me with it.
      All the best for your prep!!

  • @tushtik7474
    @tushtik7474 2 года назад

    a square minus b square is not quite
    right at 18:35.

  • @vedantkatruwar4052
    @vedantkatruwar4052 Год назад

    Thankyou so much

  • @mahicreationandarts6273
    @mahicreationandarts6273 3 года назад

    Sir for any 1^n+2^n......+n whether n is even or add formula is given but in case 5^40+6^55+8^28....how to calculate ans

    • @mahicreationandarts6273
      @mahicreationandarts6273 3 года назад

      That is if n will vary either even or odd

    • @santhoshsivan6650
      @santhoshsivan6650 3 года назад +1

      you can break the numbers and powers to simply to a simpler number like 6=2*3 , 8=2*2*2

  • @hussainpunawala6113
    @hussainpunawala6113 3 года назад +1

    24:43 but sir if here we take 2's power as 2 so ans will be 5 n it is not divisible by 3.

  • @dhananjaykumar7035
    @dhananjaykumar7035 10 месяцев назад

    According to digital sum 25 ( 2+5 =7) is a prime number because digital sum can never be 3, 6 or 9 . how????????????🤕

  • @whyclub4448
    @whyclub4448 Год назад +3

    Sir, u said 1000001 ,is NOT a prime number....BUT, if we apply the DIGITAL SUM method, its sum is not equal to 3,6 or 9...then it is a PRIME NUMBER right...??

    • @samratpatel8060
      @samratpatel8060 20 часов назад

      the statement was
      "Digital Sum of a prime number can never be 3,6 or 9"
      Nowhere its mentioned that
      numbers whose digital sum is not 3,6, or 9 is a prime number.
      ie reverse is not true

  • @bannanjehostel
    @bannanjehostel Год назад +1

    sir kuch samaj nahi aya composite numbers ke😮‍💨😥

  • @spkbusinessD--
    @spkbusinessD-- 2 года назад +3

    shivam kamat (3)
    30-7-2021
    thank you sir🙏

  • @kkkkpppp3477
    @kkkkpppp3477 4 года назад

    Sir at 14:50 you said wrong that number is prime you solved it but I think you uttered it as composite rather prime

    • @sanyamsinghi1802
      @sanyamsinghi1802 4 года назад

      the no. is composite becoz 2 is the only even prime
      and the no. in the ques was even and not 2 hence that was not prime

  • @vaibhavtharwani2285
    @vaibhavtharwani2285 Год назад

    THANKS😀

  • @NoName-pk3fw
    @NoName-pk3fw 2 года назад

    Sir why you did power of 1 to 3007