[Aptitude] Long Division, Two-Digit Division, % Calculation without Tears (and without boring Vedic Maths) using % Approximation Method

SubscribeAptitude102 Comments

IAS Mock Interviews
Ok this isn’t about boring vedic maths technique so don’t run away, yet!
  • One of  the biggest problem with IBPS/Bank, SSC, CAT, CMAT type of exams= you’ll encounter long division and percentage (%) calculation every now and then, directly or indirectly (in Data interpretation questions).
  • And If you’re not good with speed maths, you’ll waste a lot of time in such stupid calculations.

For the the aptitude questions of  Bank/MBA exams, Knowing the answer approach is not sufficient. You also need to get the answer quickly and accurately. Otherwise someone else will tick more answers and he’ll get the rank.

Consider these two questions

QuestionIn a warehouse there are 230kg of wheat initially. But rats ate away 34 kg. How much % of wheat is left?What is the answer of 196/23=?
Answer
  1. 49.3%
  2. 60.1%
  3. 85.2%
  4. 85.7%
  1. 4.93
  2. 6.01
  3. 8.52
  4. 8.57
Approach{(230-34)/230} x100=(196/230)x 100=answer196/23= answer

Everyone, even with  half hearted preparation, knows the approach. But The problem is actually in ‘doing’ that calculation or division (196/23). Here I’ll show a single method, to solve both type of calculations. As long as you know how to add two numbers, and how to multiply a number with 5, you can execute this method effortlessly.

First create a “Master Table” (don’t just read it, do this simultaneously using your own pen and paper)

100%230

Now make a new row for 50%

100%230
50%
  • So either divide 230 by 2=115
  • or multiply 230 with 5 and then shift one decimal point leftwards. (that is 1150 ==> to 115.0)
  • In either case you get 50% of 230=115
100%230
50% (half of 230)115

Now make a new row for 20% but keep it empty right now.

100%230
20%

Create one more row for 10% and simply shift one decimal leftwards. i.e. 230–> 23.0

100%230
50% (half of 230)115
20%
10% (one decimal point less)23.0

Now double the 10% number (i.e.by adding 23 into 23 again) so you get 23+23=46. That’s our 20%. Fill up the table.

100%230
50% (half of 230)115
20% (double of 10%)46
10% (one decimal point less)23.0

Our master table is ready, now Imagine there is a big water tank with total capacity of 196 lit.

We can fill it with buckets of size 10%, 20% and 50% only.
We want to fill up the tank with minimum effort. So first take 50% (115), some space will be left.
By this time you get the idea that

  1. answer is more than 50% (if % value of 196/230 is asked)
  2. answer is more than 5 (if absolute value 196/23 is asked)

so eliminate answer options that donot meet these criteria.

Move on

TankFilledBuckets
19611550%
Total11550%

There is still some space left in the tank so let’s throw a 20% bucket

TankFilledBuckets
19611550%
04620%
Total16170%

Or you can add 10% bucket two times, you’ll get same result.

It’s clear that our answer is bigger than 70%. So eliminate any options less than 70%

Hmm, so far we’ve filled 161, It can still accommodate another 10% bucket

TankFilledBuckets
19616170%
02310%
Total18480%

Now we are very close, only 196-184=12 lit. remains. But no bucket is that small!

Solution= move the decimal numbers, to create new small sized buckets.

 Master TableMoving decimal numbers
100%230
50% (half of 230)1155%11.5
20% (double of 10%)23×2= 462%4.6
10% (one decimal point less)23.01%2.3

In the exam, you don’t have to actually write new columns of 5%, 2% and 1%, just visualize them in your head, by shifting the decimal to one point leftwards.

Recall that 12 lit is empty and Now we’ve a new 5% bucket that can almost fill it up.

TankFilledBuckets
19618480%
011.55%
Total195.585%

By this time you get the idea that

  1. answer is just a little higher than 85% (if % of 196/230 is asked)
  2. answer is just a little higher than 8.5 (if absolute value 196/23 is asked)

so eliminate any answer options that are not meeting this criteria.

Still if two or more options remain. For example

  1. 8.52
  2. 8.57

^This situation usually happens in CAT Data Interpretation questions. Now what to do?

Well, Total capacity is 196 lit. and so far we filled up 195.5 so, 0.5 lit is still empty. But no bucket is small enough to carry water in this scale. Solution= create more buckets, by shifting decimal points in the “Master Table”.

 Master TableMoving decimal numbers
100%230Phase IPhase II
50% (half of 230)1155%11.50.5%1.15
20% (double of 10%)23×2= 462%4.60.2%0.46
10% (one decimal point less)23.01%2.30.1%0.23

Recall that 0.5 lit is empty and from above table, it is clear that 0.2% bucket (0.46 is very close) so let’s use it.

TankFilledBuckets
196195.5085%
000.460.2%
Total195.9685.2%

So the final answer is

  • 196/23=8.52
  • 196/230=85.2%

If you want even more accurate answer, create more buckets and proceed in the same manner.

Important sidenotes

  1. Whenever you have to do long-division e.g. 256/29, always make the denominator (bottom number i.e. 29) very close to the top number (256) and take that as 100%. That is 290=100%. And then rephrase question: “256 is how much % of 290”, then proceed according to the method you just learned. You’ll get 88.27%. but our question was 256/29. Recall that you’ve added one zero more. (290)

So, 1%=1/100

Therefore, 88.27%=(88.27/100)

And from the ‘bottom’ we take back one zero that we had added earlier. So instead of 100, there remains only 10

88.27/10=8.827 is our answer for 256/29

  1. If there is 7526/67 then? Again same method, 7526 is how much % of 6700? You’ll get 112.3%. this time we’ve added two zeros more (i.e.we used 6700 instead of 67).

So, 1%=1/100

Therefore 112.3%=112.3/100

But take back those two zeros we had added earlier. So, instead of 100, there remains only 1

112.3/1=112.3 is our answer for 7526/67

  • This method looks awkward and tiresome initially, but once you’ve enough practice of doing mental addition then it’s way easier than the Vedic Maths’ concept of double or triple digit division (because in Vedic method, many a times you’ve to adjust and carry over the numbers= not very convenient).
  • This method can be used for three-digit, four digit divisions also.
  • You can do any division as long as you can find out 10%, 20% and 50% of a number (and consequently 1%, 2%, 5%, by shifting decimal places.)

Applications of ^this method

Percentage calculation or Long Division has direct or indirect applications in following topics:

  1. Profit Loss
  2. Data Interpretation, especially those based on Pie-charts.
  3. Compound interest, Simple Interest Rate, Population Growth: by the way, they can be solved without mugging up formulas, click me to know how!
  4. Mixture-Alligiation, Wine-water, Metal alloys: can be solved without mugging up formulas, click me to know how!
  5. Time-Speed-Distance, Time and Work, Pipes and Cisterns, Boats and Railways. All of them are based on the STD formula: speed x time = distance. So there is almost always a situation where two variables are given and third is to be found= division. All of them can be solved by mugging only single STD formula. Techniques are scattered around on this page: Mrunal.org/aptitude

Test your skill

Question%Absolute ValueHint: 100% is
231/19190
181/29290
158/117117
198/6767 (because 670 would be too far)
67/5151
51/2929
158/117117
8189/5415410

Mrunal recommends

  1. (free) NCERT, NIOS, TN-Books 4 History,Geo,Sci
  2. Indian Polity M.Laxmikanth (Hindi | English)
  3. Spectrum: Modern History (Hindi | English)
  4. Maths: Quantam CAT Sarvesh Kumar
  5. Objective General English SP Bakshi
  6. Word Power made Easy -Norman Lowe
  7. Topic wise Solved Paperset by Disha

102 Comments on “[Aptitude] Long Division, Two-Digit Division, % Calculation without Tears (and without boring Vedic Maths) using % Approximation Method”

  1. good effort.. thnks!!

  2. thanku sirji…..this post really helpful

  3. nice approach ,thanks for post . i never liked vedic maths etc btw.

  4. perfect analysis thanks alot

  5. Yeah..
    Carry confusion and getting base required more time in vedic..

  6. “1.answer is more than 50% (if % value of 196/230 is asked)
    2.answer is more than 5 (if absolute value 196/23 is asked)”

    Can someone please explain how did we derive statement 2?

    1. hey vivek,
      If the original question is 196/23, then we considered 23 as 230(we placed one zero more)
      so in our answer we should eliminate one zero, so ans should be more than 5. Hope you understood

      1. Ya,You are correct.

  7. sir i am preparing for ias 2015 so i waned to do job along with my preparation soo plzz suggest me some methods to utilize my time

  8. dnt worry wake up early morning 4 clock start reading to 8 clock.Read one hour Hindu news paper.Miss prasanthi are you going to office by bus,what i want to say right two or 3 paragraph what YOU red in news paper …and memories the topic in lunch time in the evening do same as above .night while you are going bed red history topics and sleep every day 5 hours 18 months dam sure you will be selected but it hard to do that but im doing im happy …..make note note Difficult roads often leads to beautiful destination …………….all the best

  9. sir thanks for your valuable guidance.i am going to appear ibps po after 16 days.according to your experience which section among reasoning,maths and eng should be solved first and last to manage time factor.

  10. really good job at first glance it looked a tough but after some practice it seems very intersting

  11. mrunal bhai patel i want to know how to use above method when numerator is bigger than denominator ???? please clarify

    1. Hey Lincoln,
      suppose consider a sum 231/190 (Numerator bigger than Denominator), then consider only 41 (231-190) and do the sum as 41/190 and follow the same process as Mrunal Sir did. But after your final ans add 100% to the answer you get from 41/190 (if the qs is of percentage) or add 1 (if it is a normal qs). Hope you understood

  12. excellent material i have ever seen …. good job sirji…
    thank you soooo much sir….

  13. solve this question–

    if in a sale, the discount given on a saree is equal to one-fourth the marked price and the loss due to this discount is 15%, then the ratio of the cost price to the selling price is-

    a) 10:17 b) 20:17
    c) 3:4 d) 4:3

  14. Superb explanation …
    if it is available in pdf format means too Goood

  15. How will we calculate 53/81 ?

    1. 65% (approx)
      100% = 81
      50% = 40.5
      10% = 8.1
      5% = 4.05
      so here we go
      qty of (50% + 5%*3) = 40.5+(4.05*3)
      so 65% = 52.65 (close enough to 53)

  16. Hi

    Can Any One Share Agriculture insurance Company’s Previous Exams or Tell me How to Prepare for Same.

    Thanks

  17. Great work sir..Hats of to you..U made maths so easy

  18. hloz sir,,,,um preparing fr cs ,,,I found it really grt ,,,,
    thnkx alot sir gee will u suggest some books fr aptitude which contains these tricks ,,,,and how to overcome comphrension ,,,,a bit worried abt my comphrension so plzz sir help me

  19. Understood… I’ve a doubt about how to calculate numerator is less than denominator.

    Eg: 35/96, 456/982

    1. lets take difficult one which is 456/982

      100% – 982
      50% – 491

      Hence as 456 is slight less than 491, our percentage will be slight less than 50% or division is slight less than 0.5

      lets find out how much it is less than 50% so that we can get our actual answer.
      continuing percentage table,

      100% – 982
      50% – 491 5% – 49.1

      we have 491-456=35 less. Now 5% is equivalent to 49.1 so actual percentage should be slightly more than 50%-5%=45%

      100% – 982 10% – 98.2 1% – 9.82
      50% – 491 5% – 49.1 0.5% – 4.91
      20% – 196.4 2% – 19.64

      We can get 35=19.64*2-4.91 (approx) which is 4%-.5%=3.5%

      hence our answer is 50%-3.5%=46.5% or division answer is 0.465

  20. Sir, how can i prepare for ibps po

  21. okay,everyone has appreciated your efforts to show different approaches for solving quant topics and for faster calculations. but i feel these techniques unnecessarily complicate the calculations instead of reducing the time.also the std method is complicating very simple concepts which can be easily understood and learned.may be special techniques are required for cat like exams but for bank po type exams this is overly complicating the simple concepts and calculations

  22. Sir I’m preparing ibps and RBI assist exam.my English is not good plz tell me how improve my English??and study maths plan

  23. plese explian question 231/19

  24. hello sir, I have applied for IBPS PO EXAM basically i m management student. I m vry weak in maths but i m trying my best to do exam well.. can u plz guide me to overcome maths fear…

  25. Hi,

    Im from London, UK and sitting my UKCAT in september. Both of the Vedic Maths techniques and the one you showed above are very new to me. Can someone please tell me which is faster to learn and to use.

    Thanks

    Ali

  26. Actully vry nyc..sirr

  27. Thanks Sir for the concepts

  28. Thank you very much

Leave a Reply

Your email address will not be published. Required fields are marked *