Simple Equations 5 | CAT Preparation 2024 | Algebra | Quantitative Aptitude

[@anushajain2813]

i am really grateful to you sir even the paid coachings does not provide such a systematic and well explained concept videos it feels like i wasted money in that coaching centre. now i am really getting hold on concepts. thank you so much sir

[@namansharma2721]

It's kinda comforting to know I am not the only one who wasted his money and then came here 😂

[@314shubhanshujaiswal9]

@@namansharma2721 which coaching bro?

[@opnoobda8557]

@@namansharma2721 me also🤣🤣

[@_ravi_baghel]

Ravi prakash sir is the real guru, I never seen such content for free. Thanku sir from bottom of my heart❤

[@anjalimalar3050]

Ur always telling that we can play with numbers in anyway.... Realizing it slowly 🥰🥰🥰🥰

[@himanshumaurya7317]

Your effort towards us ...... Can't imagine how much you are passionate towards student to give them quality and free education Sir once in a life I will meet you.... It doesn't matter I will succeed or not but i will

[@abhisheks6458]

You are truely an inspiration. Whenever I feel like its enough for today, I just see the efforts and interest you have. This motivates to study longer. Thanks sir 🙂

[@MIAmor333]

after watching so many videos and finally for the first time i m commenting that you are an extreme example of greatness..and thats what is intriguing among students...well explained Mr. Ravi...

[@thornplato9844]

Or another method in solving last question is that after finding two extreme digits we know that RHS i.e 8cb2 is divisible by 4.So according to divisibility rule of 4 last two digit should be multiple of 4.So b can be either 1 or 3.N further we can try guessing method for c.Thnxx sir ur videos r really helpful.

[@Jai14best]

lol b is 7

[@priyac1938]

@@Jai14best b is 1. C is 7

[@jatingupta4912]

By divisibility rule, b can be 13,5,7,9. So I don't think we can use this .

[@arnoldterry8689]

@@Jai14best Funny.

[@dewanshukewat2664]

great use of logic sir...u made it look so simple...the way u approached that question was remarkable

[@harman5710]

I don't know whether my CAT 2023 will be clear or not but the knowledge I am getting is precious

[@Rodha]

Hoga. Always think positive

[@brokenarcade2265]

how much u scored bro?

[@AyanAnsari-kr3it]

What's your percentile?

[@himanshusahani4238]

Being a UPSC aspirant, your lectures are great help for CSAT exam. Thank u so much

[@govindakagamingbros3214]

Last question solution....just wow, i literally wrote wow two times in my notes.

[@muskaandatta9233]

totally loved the quality of questions in this video

[@HIMANSHU_00753]

at 10:15 for people who are confused with the sir's solution. let me tell you, we can make either a = 0 OR c = 0. We cannot make both the numbers ZERO at a same time. since it is 3 Digit no. and cannot be represented taking the values a = 0 and c = 0 at the same time if it so happens values will be of 2 Digit. it is totally up to you either make a = 0 or c = 0.As sir had taken c = 0 that is why he couldn't have taken a = 0. correct answer is only = 8 solutions. correct me if I am wrong. I'm CAT 2027-2028 Aspirant.

[@Hokage982]

You are probably wrong. Cause sir didnt take 018 as a value cause 018 is basically a 2 digit no i.e 18. And here we need 3 digit values...

[@HIMANSHU_00753]

@@Hokage982 exactly, na we cannot the front digit as zero...

[@070garambhakrunal4]

Bro total number of solutions is 9

[@HIMANSHU_00753]

@@070garambhakrunal4 8 hi hai bhai

[@satvikverma3145]

​@@HIMANSHU_00753 9 solutions as you can check once as a=0 and c=8 and also a=8 and c=0. These 2 and the remaining 7 cases total is 9 solutions. Try substituting the values for the above two case in the question you will find out yourself.

[@jatingupta4912]

At 10:00 a+c can also be 0 ,8. So total values will be 9 right?

[@riyathakur8892]

If a=0 then it will become 2 digit number

[@jatingupta4912]

@@riyathakur8892 but we are also considering cba and we are taking c as 0. So why can't we take a as 0

[@dhonisingh4706]

@@jatingupta4912 abc is our 3digit assumed number....018 would make our assumption itself wrong

[@kapilsarkar9223]

@@jatingupta4912 the question is there are how many 3 digit numbers when added with reverse sums to 828 . now this automatically cancels the first digit as zero . but when reversed the first digit can be zero . thats how it is considered .

[@sharedu316]

@@kapilsarkar9223 Thanks for this, it helps a lot. I too had the same doubt.

[@suryavoroy3527]

very tricky stuff ,will rewatch a couple of more times! Nice video!

[@anishchakraborty378]

In that first 4 digit sum, 14:50, if u consider a & d as 7 & 0, then if the number is reversed 0 will be in front and hence it will be a 3digit number

[@meghanaprasad2638]

We do not have to worry if reversing it gives a three digit number. We should only focus, if the difference between original and reversed number remains 7083.

[@sharad9509]

i just feel really grateful, coming from an underprivileged section, these are AMRIT

[@aniketsingh1693]

sir i have done full playlist of ur questions of algebra , should i be relaxed that all topics and various questions are covered? i have understood this much and slved some questrions as well

[@pranavparashar8088]

Last question is just hit and trial. After writing the conditions i tried to cancel the numbers so that the RHS is equal to zero.

[@HereToSay]

9:56 sir, shouldn't we omit 0 for both a and c, since the reverse of the number, i.e. cba will become a 2-digit no if c is 0?

[@techfin-ly1oj]

one doubt : In last question, why 'c' can't be more than 9

[@sidharthnair881]

Hi Sir, we consider 05 to be a 2 digit number right, then in 17:20, why aren't we considering 0 as a possible digit for a? Will 0999 not be a valid 4 digit number?

[@rajumourya3062]

at 10th min value of A and C cannot be 0 because it turns them into a two digit number and A+C=8 then total ways be 14 for example (1,7) and (7,1) and soon.SIR clarify if

[@ashutoshkothawal6165]

at 10.23 Values should be 9 As (0,8) Combination of a and c is also accountable.

[@arskandan]

the reason is that if the no. is 018 which is ultimately 18 and it is a 2 digit number, hence it is not taken.

[@alt9136]

Same applies for 8,0 as well...coz the no. Will be 810 and on reversing it will be 018 which is a not a 3 digit.

[@namansharwan66]

@@alt9136 ques says that we've taken a 3 digit number, no where explicitly mentioned that reverse also needs to be 3 digit number, hence we can take "a" and "c" as 8,0 but not vice versa

[@Lukeicht19]

@@namansharwan66 idk how but if you accept the fact that abc reverse is also a 3 digit aren't you contradicting your own statement by taking a and c as 8 and 0 cuz the reverse is definitely not a three digit number

[@anill_19]

Last question was damn!! 🙌🏼

[@brozoro2545]

Q. A 4-digit no when reversed dec by 7083. How many such nos. are possible? DBT: a-d = -7 and b-c = -10 will also satisfy the equation. So number of solutions should be double if we consider the negatives also. Pls clarify.

[@Rodha]

Digits can't be negative

[@sreyashroutray811]

It would yield -787 and not 787. Check

[@nareshch3501]

At 10.25, in the last we take no of solutions (0 8 ) is missing which makes solution 9, am I right?

[@ajithkumaar3473]

no,018 will become 2 digit number. hence only 8 solutions

[@DevendraSingh-hs1gj]

@@ajithkumaar3473 then (8,0) is also not possible as cba become 081 thus only 7 solution

[@thehindiskull9214]

@@DevendraSingh-hs1gj bro its posible because abc is an 3 digit number so there is no clarification about Cba so we have to consider abc as a 3 digit number answer is right 8

[@kapilkothari8272]

The question didnt say abc is a 3 digit number so it should have 9 solutions

[@dhruvsharma9083]

@@kapilkothari8272 it said that its a 3 digit number.

[@Sfrab]

Why did we consider 8,0 in the first question ,bcs 008 wouldn't be a three digit number..ryt?🤔

[@ektagupta1701]

At 25:43 , sir I think answer should be 18 because question is asking sum of digits of that no.

[@anjankashyapb1373]

yep 2+1+7+8

[@deringlangthasa6362]

In the LAST QUESTION I CANT GET 2C-1/13

[@satnamsingh-lh7iv]

Sir we can take value of b from 0-9 anything becoz Multiplying 20 by any thing will be 0 so b as 2,3,4..... Is also possible

[@DhruvChawla-r5x]

In the first question at 4:33 , why did we take the case where a=5 and b=0? The two digit no. becomes 50, reversing it gives 05. Similarly in second question, 8b0 when reversed becomes 0b8 where b = [0,9]. Please explain?

[@namansharma2721]

Question doesn't mention that on reversing, the number should REMAIN a 2-Digit number

[@HIMANSHU_00753]

at 10:15 solutions are: (A,C,B) and here B is from 0 to 9. A, C - - 1, 7 2, 6 3, 5 4, 4 5, 3 6, 2 7, 1 8, 0 OR 0, 8 (any one only)

[@mohakpal7970]

08 is rejected coz 018 is 2 digit number

[@HereToSay]

C shouldn't be0 either, since the reverse is cba and 0__ would be a 2-digit number!

[@debarshiaich8320]

Sir Last Question is an absolute gem .

[@aayushpatel6581]

If assumed abc and cba has to be a 3 digit no. Then 1 set of ac and ca i.e a=0 c= 8 and a=8 c=0 neither will qualify. a. c 0. 8 8. 0 Assume the cases 018+810: 1st case abc+cba. 810+018: 2nd case abc+cba If abc is 2 digit in 1st case and cba is 2 digit in 2nd case then how will both qualify? Total, 9 cases - 2 cases= 7 cases ?? Am i right?

[@sarthakbansal564]

there's a lot of confusion in the 2nd question, hope this will clear it 'a' cannot be zero since abc is the initial 3 digit number , so keeping 'a' as zero will contradict the question, but keeping c as zero will make no such contradictions

[@aniketrajapure4060]

In first question , a=5,b=0 you have taken which is wrong i guess , coz in question they said 2 digit no when reversed . so when we reverse no it is 05 which is wrong . KINDLY REPLY , thanks

[@HarshGupta-ts9rv]

Yess exactly, was searching comment for the same

[@yashasvsingh458]

in last question its asked sum of digit of reverse of that number. so, answer should be 2+1+7+8=18. right?

[@avitherapy22]

Last Qs blown my mind TYSM

[@shubhamchhalani9978]

The last question was Fantastic ❤❤

[@snehilgour-d9l]

hands down to you sir such a great level of question with more great level of explaination : )

[@jaypatel7632]

Excellent 🎉

[@mvcreat908]

Stupendous sir🙏

[@geetpandey3612]

At 7:00 if we take (8,0) . The number 810 when reversed becomes 018 , which is a digit number. Sir please explain this..?

[@gadiadivya102]

yes so 810 - 018 = 792

[@vishesh_raina]

Thank you Guruji

[@consumer_55]

really enjoyed the last question

[@akhilb3196]

Sir i have a doubt that if the 3 digut number end with zero when we reverse it that becomes 2 digit number ryt then how can we conclude both the emwith zero and non zero last digit..

[@ss590]

Last Question was awesome ❤ Thankyou 💜 so much sir 😊

[@rohitpatel-s3q]

10:29 ans is 9 values sir missed a+c=8, a=0 and c=8 and and rest of the values are written .... 10:29

[@prashiq]

10:22 here a and c can take values of 0 and 8 respectively..? please confirm.

[@namansharma2721]

Thank you so much sir!🙏🏻🙏🏻♥️♥️

[@traders_chart_Lab]

0, 8 can also be a factor in abc + cba = 828 qus , hence there will be 9 values to a+c =8

[@karthikachandran5348]

yaa i thought the same its 9 .

[@karthikachandran5348]

but if a is zero in abc , it will be just bc a two digit no, qst says 3 digit,so 8,0 is possible not vice versa

[@traders_chart_Lab]

@@karthikachandran5348 got it, thank you

[@HIMANSHU_00753]

but why are we taking C = 0 , it will turn our number be 2 digit, too.@@karthikachandran5348

[@Error-oi9ms]

Should we exclude (7, 0) as this will not form 4 digit number?

[@jaidevtyagi1033]

if a 4 digit number is reversed does it have to be a 4 digit only?? if that is the case then unit digit can never be 0 or can we say that numbers with unit digit 0 don't have a valid reverse number?? 2040's is not possible?? if we reverese 2020 it's not 0202 or 202??

[@PrabhuKalyanMishra]

i have a doubt in abc+cba=828, why we consider b=0 and ans is 8 no.?

[@Super-lj1rf]

for question no 3 answer should be 9 instead of 8 ,a can take 0 and c can take 8 values sir missed in explanation

[@kishlay_thakur]

If a will 0 then it will become 2 digit number

[@dharmareddy8831]

For question Abc + cba = 828. Why 0,8 is not considered but 8,0 is considered

[@anantnarayandwivedi9169]

14:52 sir how can we put d=0? When we reverse the digits it wouldn't be a 4 digit number then..

[@carpediem9407]

why dont we directly multiply all options and see

[@omkesharwani9834]

10:15 sir i guess 0,8 wont be the answer we cant take 0 as c ki value otherwise cba 2 digit number ho jayega rightt

[@RishabhSingh-qd7eu]

23:00

[@ishanduttsharma460]

at 10.25 , shouldn't the cases be 9

[@careerroute392]

सर आखिरी क्वेश्चन 1% भी समझ नहीं आया आपने 4 (abcd) को कैसे मल्टीप्लाई क्या समझ नहीं आया अलजेब्रा के क्वेश्चन हार्ड लग रहे हैं कुछ ट्रिक बताइए जिससे इसे आसानी से सॉल्व क्या जा सके

[@deeksharai1229]

Thanku sir

[@agrawalhitesh2670]

12:00 Q. A 4-digit no when reversed dec by 7083. How many such nos. are possible? Doubt - A = (9,8,7), B = (1-9), C = (0-8), D = (0,1,2) Then ABCD = (9982 - 7100) i.e. total no of solutions should be 2883 not 27, Pls clarify

[@geetankarkarmakar378]

D can have only 2, 1, 0. At the same time A needs to have 9, 8, 7 respectively. When D = 0, you can't put A=9. Hope you are getting the logic. Also, if you see, you can't randomly put numbers. You will have to create sets which when reversed and took difference, gives 7083. For example, According to your possibilities, after 9982, if you change D, you will have to change A also since the difference between A and D is always constant. If you take A= 8, then the one of the numbers can be 8981( difference between A and D = 7). 8981-1898 = 7083. But 9981- 1899 is not equal to 7083. It wont't ever take a value like 9981(Difference between A and D not equal to 7) or 9980(Difference between A and D not equal to 7) or something of this sort. Please consider all the 4 cases together. You will gradually realise that only 27 such numbers are possible between (9982- 7100).

[@pareshrathour]

@@geetankarkarmakar378 D can never be 0 (as per qn, it should be a four digit number)

[@PRAVEENCHOUGALA-mu8xv]

In 3rd question how can (a,c) 8,0 make cba three digit number...can anyone pls explain

[@13GameZone]

Bro C can be zero but A can't be

[@cumulusmusic100]

Thank you Sir 🙏

[@technocobraa9279]

Question in this video are 😍

[@Viiisheshk]

Sir please tell the source of questions.......Please....!!!

[@preetimishra2237]

Why hv we not considered b can be any no from 0 -9 In abc+cba=828 wala question

[@salonigupta8252]

i agree- we can take b=any set of values as well

[@sandeepkumarbehera5458]

awesome video

[@sharathramachandran]

At 9:18, a+c could be equal to any two digit number ending with 8. If need not necessarily be just 8. Could somebody kindly clarify this doubt. Thanks.

[@sidanshajahan9212]

If a+c is a 2 digit number (let's say 18), then 101*18 in itself exceedes 828 na?

[@hitanshugala7993]

How did he end up with 8 values ?

[@dhruvsharma9083]

@@sidanshajahan9212 thought of the same.

[@sachinkumarsingh2518]

As per my approach is wrong , answer will be equal to 9 Nos. instead of 8 values.

[@jaikishanyadav79]

@@hitanshugala7993 i think there will be 9 values

[@harnamsingh2004]

8,0 should not be an option as if either of a or c become 0 then the number is not a 3 digit number

[@tanvinimbalkar6977]

810 will reverse to 018 so isn't it wrong as in reverse it became a 2 digit number??

[@xerxes5592]

Sir the 3 digit question at 5:20 exactly similar question with figures changed, came in cat 21 slot 1 .

[@reconultronyt7152]

At 9:16......we assume b as 1........but please anyway explain me why be cant be any number because 20*b must be zero at last digit ...which also satisfies the equation...

[@arunapatel7538]

It was not assumed as 1 when a+c is 8 828-101*8= 20b so b =1

[@arhamsiddique3512]

This is a continuation of which video?

[@nitish01shah]

Sir at 10:19 we if take possibility of c=0 and a=8 , it will make cba a 2-digit no....so why we didn't eliminated that case ??.

[@subhamjain3037]

If a cannot be 0 then even c cannot be 0.

[@111inayatkhan4]

In the first question how (10a + b) - (10b - a) = 45 becomes 9(a-b) = 45.please explain anyone

[@lakshaygupta2816]

Last ques was lit!!🥵

[@avinashnair8433]

In Last question, they asked for sum of digits. But only the no. was found out. So ans will be 18, ri8??

[@swatibisht4572]

Yes

[@michaelnivitha5222]

I think it will be 9. As they have asked for sum of the digits we should add 18 also as 1+8=9. Hence the answer will be 9.

[@swatibisht4572]

@@michaelnivitha5222 no it can't be. I don't think so. There are 4 digits whose sum are 18 that's it. Why do we even have to go further?

[@AllTogether77]

@@michaelnivitha5222 they asked to find sum.... Not digital sum

[@michaelnivitha5222]

@@AllTogether77 Okay

[@naveenkr8436]

At 10:20 ,when 8,0 is taken into account,then why not 0,8 ?

[@Rodha]

3 digit no. cannot start with zero

[@garimasahu193]

How's c=0 possible?

[@Shashank-dm5ud]

Can someone explain me at start 3:20 why it is taken as 9??

[@simplethings7000]

10a-a = 9a 10b-b = 9b 9(a+b)

[@Bhavesh_jattan]

Thank you so much sir for the best content .. Sir but how to read analyse and come up with a thought process and devise a way to solve the question in just 2 minutes

[@divakarbeingDIVAKAR]

it is not said, no. cannot be repeated. if that condition given, your answer will be correct.

[@memallikag]

At 19:05 why can't a=1 because it will be even when multiplied by 4.

[@smitvara1614]

Sir in last question b=2c-1/c how?? Even if we divide by 30 both side it will either 2c-30 or 60c- 3.

[@deringlangthasa6362]

exactly

[@yashasharma9963]

Thank you, Sir. Great session. 👍

[@krishsureka8419]

7.14 if c =0 than cba will be a two digit number

[@piyushmalhotra611]

In the question where abc + cba = 828, shouldn't it be 15 values possible? as if a&c are 7&1 and a&c can also be 1&7 and goes for every 7 values which becomes 14 values and 1 value is where a&c are 8&0, so the total value becomes 15? As the equation is in addition. Please let me know if I am wrong.

[@nirmalrawal7494]

Just try writing all the no. U will get it :) . Just keep in mind the no. Has to be a 3 digit no. And its reverse may not be a 3 digit no. (Not our concern)

[@hannahanneabraham97]

He included all the numbers you mentioned to get 8 values. As in, since a + c = 8 and b = 1, the combinations of a and c are (8,0) , (1,7) , (7,1) , (6,2) , (2,6) , (3,5) , (5,3) and (4,4). So that makes 8 values.

[@sachinbhuvanes4000]

​@@hannahanneabraham97 I don't agree with (4,4) which means a=4 , b=4.... Which was no possible.

[@vaibhavarora9784]

10:15 why (4+4) is considered as equation is a+c=8 so nos has to be different?

[@Lukeicht19]

Its unit digit by that question means 414+414 is also a possibily

[@urname855]

​@@Lukeicht19but 4 and 4 are equal And I think we should take a and c distinct Isn't it Please clerify

[@itsprolayonline]

In 4 digit no problem .if we take d as 0 no would become 3 digit .why would u take 0?

[@swatibisht4572]

Even If we put b, c and d= 0, it'll remain a four digit no. And as for the reversed condition it can be a 2,3 or 4 digit no. For example. If we take no. As 7100 it's reverse will be 17 and we'll get the difference as 7083. Hope you got it now.

[@shubhamSingh-ly2kl]

Damn this was good

[@Om_Parmar]

10:15 pe A plus C 8 hein to a is equal to 0 aur C is equal to 8 bhi to ho skta h nah. to total 9 aayega

[@shriyachopra2148]

Even I had this doubt

[@shriyachopra2148]

If a wil be zero the number will not be a three digit no

[@AJ22549]

sir,in question 2 ,we have got the value of b=1. Then with ordered pairs(1,7),(7,1) the digits becomes cbb and bbc right...I think the no of solutions for the question should be 8-2=6. please let me know if i am wrong

[@navneetmaurya5297]

you have to take all the possibility. so 8 is correct

[@ironmanwillbeback5541]

At 19:50 how you take 8 pls anyone clear my doubt

[@Shubham-wv6tf]

How 2500 came please tell me someone

[@Deardiaryyyyyy]

Hey, so basically the smallest five digit number is 10,000 and if we need a 4 digit number even after multiplying our number "abcd" into 4 so we divide 10000 by 4 to get 2500 which tells us abcd is less than 2500. I tried to explain as best as i understood. Hope it helps:)

[@deringlangthasa6362]

i think sir last question is has an error in calculation

[@yuvrajbangar568]

Can anybody solve this question for 729???? How many values are possible

[@ananyayhehe]

how did d become either 8000 or 9000 something. can someone break it up for me ?

[@naveenkamath907]

4*2000 (as a = 2) will make something 8000 or 9000 in rhs, it shouldn't exceed 10k so 8 or 9

[@ananyayhehe]

can someone please explain in the last question why the number cannot exceed 2500

[@ananyayhehe]

okay i got it. it says less that 2500 which implies it cannot be 2500. since 2500 x 4 = 10000. so the number cannot be 2500. it needs to be 4 digit number when 2499 x 4 = 9996

[@deringlangthasa6362]

hey can you explain how its 2c-1/13 ? i tried several times its always 20c-3/13

[@Deardiaryyyyyy]

@@deringlangthasa6362 okay so when you take 400b-10b+30=60c then it becomes 390b +30=60c now see 390, 30 and 60 are all divisible by 3 so reduce it all to 130b + 10=20c and now removing all zeroes since all are divisible by 10 we get 13b=2c-1 and at last b=2c-1/13

[@RoshniKumariBBASEMSECTIONB]

10.57how come 27integral solution it should de 12 know please someone clarify my daout

[@RoshniKumariBBASEMSECTIONB]

We should multiply or add