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

Number System by Ravi Prakash | Quantitative Aptitude for CAT 2024
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[@nishanthhonna8406]

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

[@experimentointerneto902]

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

[@GOKU-tt6zl]

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

[@Someone7676]

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

[@Harrystyles0004]

@@Someone7676 sahi kahe bhai

[@hetbhatt9441]

What was your cat score

[@shruti9557]

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

[@ArvindJaiswal-x8r]

❤❤

[@vijayaj9691]

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]

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.

[@kavita6004]

100 ko 10 raise to the power 1 likhta hai ya 2 ??

[@Subhashreepriyadarshini]

​@@kavita6004 100= 10^2= 10×10

[@navreetkaur1215]

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]

Op 😂😂

[@Nilotpal_Chakravarty_]

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.

[@saikhzikrullah2628]

973 is not a prime number, it is divisible by 7

[@kishorparab2078]

973 is not prime no.

[@aminahamadkhan3766]

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 ???????????????????????????????????????

[@hiraburney3123]

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.

[@aayushikashyap_]

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😊

[@amitsahu4782]

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

[@digvijaysingh1997]

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???

[@Atul-zz2ck]

Please watch at 6:00 he is saying to find prime no. We have to take square root then find if the no. Are divisible and I got to divide from 31,29,23,19,17,13 till 2 from which 19 is divisible so it is not a prime no.

[@tanvigupta4842]

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

[@Awesomeyashh]

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

[@bannanjehostel]

sir kuch samaj nahi aya composite numbers ke😮‍💨😥

[@batulrizvi8390]

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

[@brajmohanupadhyay1753]

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

[@sushantjha8373]

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]

Thank you

[@jibinjoby9523]

Bro did u wrote cat exam

[@zoro3188]

@@jibinjoby9523 yes I did

[@AyushKumar-wl8cx]

@@zoro3188 Coaching ya self study bro??

[@hetbhatt9441]

What was your cat score?????

[@jinujain8321]

Tbh for basis not worth it - he uses concept that a normal person can't understand

[@Rodha]

Why can't u understand ? Put pressure on your mind.

[@spkbusinessD--]

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

[@official.frostburn]

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.

[@ahmedshaikh6053]

Thank you so much sir for this awesome session❤️

[@whyclub4448]

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]

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

[@donaldrook9359]

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

[@Ok12376]

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

[@bhavyalukka601]

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]

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]

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

[@dineshkhandelwal6725]

you said by digital sum we can see if a no. is prime or not , so tocheck 1000001 is prime or not when we add we get 2 so it should be a prime no right ? why did u say its not prime?

[@Brad-ne6ld]

I was thinking the same, did you got the answer???

[@AyushPandey-ys6yy]

How he take that 1³ any logic bina kuch bataye le le rha hai how we know we have to take here 1³

[@omagarwal2688]

1 ki power kuch bhi le skte ho 1 hi aayega dusre ki power se match karke

[@mengwalgamingff9581]

bro first you need to clear your basics.. they have separate play list for this so check it.. ❤

[@nikhithamk5865]

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?

[@rhutvigawai5672]

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

[@tusharrj6578]

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]

@@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.

[@yesiamnoob9192]

​@@yashmehrotra6201nice explanation bro 💜

[@sarthakpatra9261]

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]

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

[@kundanahmed4465]

This channel brings out the logic behind numbers. All of these are available in books, but the way he correlates stuffs makes learning an enjoyable exercise.

[@durgamishra7994]

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

[@rahulgeorge7502]

reverse is not true.

[@atharvakakade8021]

973 is not a prime number dude 139x7=973

[@FunkyyKidsTV]

Sir questions smjh m nhin aaye 🥺

[@poojab4967]

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

[@harshithaksubramanyam6135]

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

[@abhinavsharma341]

@@harshithaksubramanyam6135 pta lge toh meko bhi btana

[@shivampruthi6833]

​@@abhinavsharma341mujhe bhi bta do

[@gethingeorge4140]

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

[@AryanSingh-vi1oz]

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

[@IshankChoudhary]

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

[@iamdavidaman]

Digital sum of prime no. Will never 3,6or 9 but what about other numbers for ex 1234562 gives a digital sum of 5 and it is not a prime no. Can anyone help ?

[@rayzoldyck8044]

gotta check for all the conditions

[@iamdavidaman]

@@rayzoldyck8044 it will be more time taking if i start checking for all 4 conditions

[@shivamsaini1591]

The p2-1 and digital sum method doesn’t apply to 973., they both give 973 as a prime number where it is not.

[@tiktokreel92]

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 ????

[@TheDHemant]

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?

[@KK-mb2vy]

13:29 to be continued

[@ujwalkachade3459]

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

[@kan-nas]

yes, it wont be divisible by 3 if you take 'n' as 2, because 2 is an even number.

[@Ridhima-ki3wh]

Q - Is 1000001 prime or composite? Sol - We can simply check the digital sum and hence it is not a prime no. Is this way wrong?

[@PRATHYUSHAVENNAPUSA]

I think no we shouldn't apply because if the number is a prime number for it's checking only we can apply that

[@PRATHYUSHAVENNAPUSA]

Here digital sum is 2 know according to the rule it should be a prime number but it is not a prime number

[@samratpatel8060]

@@PRATHYUSHAVENNAPUSA when the digital is 3,6 or 9 we are SURE that the number is not prime when the digitalsum is something else we conclude that we are UNSURE hence have to resort to using other option

[@nikhiljindal4580]

2^4 + 1 , in this case according to the lecture it should be divisible by 3 , but 17 is not divisible by 3. Is the rule wrong or are there some exceptions?

[@vinaymetri7706]

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

[@maitrisinghai]

bas ye hi comment dhoondh rahi thi

[@manjunathkalal987]

Sir i am prepairing cat2023 this syllabus is ok

[@KhushiKumari-ll2ru]

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

[@UrviThapliyal]

Can anyone tell the video after this? In the playlist factors come next but in the starting of that video sir says we have done quite other things as well.

[@kumarabhishek1064]

when we have digital sum technique which is way easier, why we use other methods to find prime ? are there any constraints of digital sum method ?

[@iamtobi9632]

I am so dumb that i cant even understand it 😭

[@swatishivabal6093]

Istg same

[@rakshitmittal6288]

Sir, Pdf notes are available of these videos.

[@spyder2374]

4:28 Prime no less then 11 should include 5... But it's not a matter, ..just bother me. So much writing mistakes...😒😒☹️

[@manishramesh9344]

Yeah it must Include 5

[@aadishjain7454]

Bhai free m jaan lega kya

[@spyder2374]

@@aadishjain7454 bhai accuracy is one of the most important factor while solving.....CAT

[@mahimanigam3475]

Tera naam to happy hai ??!!

[@piyushkumarsingh3439]

Part 4 is missing sir

[@Khushi.tawari1535]

6:27 Do it for 683 ???

[@ShreyashChopade]

683 = sq rt. 683 = P

[@vidhivora3952]

❤❤

[@1morerep491]

Please explain the last question

[@d_41_nikhilpurabiya47]

731 is 6*122-1 how is it not prime

[@dhananjaykumar7035]

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

[@LivingWithSwastik]

Was liking it, but then continuous confusion in putting 0s, writing formulas etc started me to put in doubt, if I learn something now and that is a +- mistake of the teacher then I'll be the one confused going ahead, sad😢

[@nothing9021]

It is not true what you tell....one is square of p - 1 is always divisible by 24...how it can be possible....for all cases...like p= 6n+/-1 then i found 36n2 +/-12n if 2 then you right if 3, 5 , 7, 11 then you wrong. So please tell how we apply this equation in correct way....secondly you told that prime number finding formula is 6n+/-1 then you tell one example of 25 but it is not a prime number....so pls correct the formula and tell which numbers, in this case, it is not applied.

[@Tara-vh4yk]

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]

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

[@eyaShukla]

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!!

[@hussainpunawala6113]

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.

[@kamyakharya7776]

2 is a even power....

[@nazamwasi3357]

973==9+7+3 19==1+9 10=1+0 1 can we say 973 is prime number from digit sum method.

[@titikshauniyal3463]

How is 1000001 not a prime number ? It is divisible by 6 and giving -1 as remainder . Please explain...

[@honeyplays4626]

in 6k-1 ,reverse isn't true and 1000001 can be factorized is 101 and 9901

[@kinzakhann]

Hey did you get this if yes pls tell 🙂

[@divyanshumishra9440]

sir 111 ka 2112 kadigital sum to 3 or 6 aa rha hai to kya ye number glt hai

[@curiosity9861]

111 has more than 2 factors 1,3,111 and 2112 is an even number so as mentioned in the video only one even prime number exist which is 2 so 2112 cannot be a prime number

[@divyanshumishra9440]

@@curiosity9861 thanku bhai

[@FunkyyKidsTV]

Sir ismein itne tricks and method h I will forget what to do sir?

[@yuktisharma50]

practice

[@AnkitaSaha-f1p]

Hello, thank you and very good explanation of the concept but where can i find the sums to solve? i need sums to apply the concepts.

[@dineshbabu8831]

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

[@anuragtripathi4040]

at 4:38 you should also check with 5

[@keerthanachandrasekhar]

no need, it is common sense, 114 does not end with 0 or 5

[@Antivenom932]

Sir i will get 99% this time

[@malavikamadhav7345]

Thank you sir for your class🙏Greatful for your dedication❤

[@vikaspal3047]

Prakash prakash Ravi Prakash😅

[@shrutipandey3113]

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?

[@Aditya-ol8ev]

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

[@nahishgupta4446]

100001 , the digital sum of this no is 2 , and not the 3, 6,or9 , so why cant this logic works here

[@milindpelagade6524]

Why didn't we use the concept of digital sum in 100001 problem??

[@utkarshtripathi2600]

Coz digital sum to find prime number says that if sum is 3,6 or 9 it cannot be a prime number, but other then that the digital sum can be 1,2,4,5,7 or 8 and we then need to check it by other methods.

[@amithkumar8044]

We could've used 6k+1 method right? I.e 10^6+1

[@AashishKumar-km2bd]

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

[@intisabilyas7474]

6:28 done till here

[@aryaman7142]

thank you sir

[@aakritimittal4610]

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

[@vinaychauhan983]

sir is on unacademy now

[@dupkinhouse3159]

in your last example , in 973, if you do by digital sum. it is coming prime as digital sum comes to 1. then why the ans are coming diff in 2 ways?

[@vanshitadev5089]

Ans can be diff but when it's 1,we know that digital sum of a prime no. cannot be 3,6, or 9..so it is a prime no. Similarly when a-b i.e. 10-3= 7 which is divisible by 973 is proved..that means it a prime no.

[@eshaandevnani]

what about a to the power 4 plus a to the power 2

[@blackhunter3757]

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

[@gunvitsingh3371]

This All Vedioes will help in GATE SSC BANK EXAM ?

[@JanviVerma-u2k]

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

[@TheDHemant]

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?

[@RSNsince]

As in last part 7 and 3 r always divisible so it's composite rt

[@Sahibaamir]

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

[@officiallodhi3967]

Better than unacademy ✌✌✌✌✌✌

[@tanishkamunjal2222]

Sir, please recommend a book where we can practice the concepts taught by you. will be highly grateful :D

[@pranjaltripathi1027]

Arun sharma. Iahve pdf of this book. Its famous book for Quant

[@mahimanigam3475]

@@pranjaltripathi1027 you have the pdf ?? Can u share it ?

[@allall8695]

@@pranjaltripathi1027 Bhai sahab. Can you share it with me as well? Is via mail okay? If yes, my email is : [e-mail]

[@pranjaltripathi1027]

@@mahimanigam3475 Okay i wil send

[@pranjaltripathi1027]

@@allall8695 okk sure

[@nahishgupta4446]

When we divide 100001 with 6 , the remainder remains will be 5 , so the test wil be failed here

[@sudhirpatel3696]

day -1

[@blossomshrivastava8834]

Example: Is 100001 prime or composite? If we do this by DIGITAL SUM method then sum will be 2 and its prime right? Please let me know where I understood wrong.

[@samratpatel8060]

when the digital is 3,6 or 9 we are SURE that the number is not prime when the digitalsum is something else we conclude that we are UNSURE hence have to resort to using other option

[@pradipto_de]

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

[@abhijeetsingh9084]

Is there any video where this topic is continued

[@Indiangourmet]

Same question vdo mila ?

[@yashaswinitg9299]

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

[@LearnsomethingXYZ]

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

[@lazybeastrahul]

21:05

[@udaykiranuday1493]

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.

[@aminahamadkhan3766]

15:39

[@Amansingh-uh1it]

Sir, digital sum of 1009 is 10 but that’s a prime number how ?

[@shubhammaurya6656]

Digital sum means number ko 1digit me lana hoga 10 is written as(1+0=1)

[@Amansingh-uh1it]

shubham maurya thankyou