Maths Posts

Since there are a fair number of posts up by now, finding an old post on a particular topic might prove troublesome. This page will provide quick links to the older posts. We’ll update it at infrequent intervals 🙂

Probability – 18

Probability – 17

Probability – 16

Probability – 15

Probability – 14

Probability – 13

Probability – 12

Probability – 11

Probability – 10

Probability – 9

Probability – 8

Probability – 7

Probability – 6

Probability – 5

Probability – 4

Probability – 3

Probability – 2

Probability – 1


17th Algebra – 16

15th Algebra – 15

10th Algebra – 14

8th Algebra – 13

3rd Algebra – 12

1st Algebra – 11


26th Algebra – 10

24th Algebra – 9

19th Algebra – 8

17th Algebra – 7

12th Algebra – 6

10th Algebra – 5

5th Algebra – 4

3rd Algebra – 3


29th Algebra – 2

27th Algebra – 1

22nd Logs – 10

20th Logs – 9

15th Logs – 8

13th Logs – 7

8th Logs – 6

6th Logs – 5

1st Logs – 4


29th Logs – 3

24th Logs – 2

22th Logs – 1

17th Puzzles – 20

15th Puzzles – 19

10th Puzzles – 18

8th Puzzles – 17

3rd Puzzles – 16

1st Puzzles – 15


27th Puzzles – 14

25th Puzzles – 13

20th Puzzles – 12

18th Puzzles – 11

13th Puzzles – 10

11th Puzzles – 9

6th Puzzles – 8

4th Puzzles – 7

Feb 14

27th Puzzles – 6

25th Puzzles – 5

20th Puzzles – 4

18th Puzzles – 3

13th Puzzles – 2

11th Puzzles – 1

6th Sequences – CAT Scan – 8

4th Sequences – CAT Scan – 7


30th Sequences – CAT Scan – 6

28th Sequences – CAT Scan – 5

9th Sequences – CAT Scan – 4

8th Sequences – CAT Scan – 3

7th Sequences – CAT Scan – 2

6th Sequences – CAT Scan – 1

2nd XAT Scan – 8

1st XAT Scan – 7


31st XAT Scan – 6

30th XAT Scan – 5

26th XAT Scan – 4

25th XAT Scan – 3

24th XAT Scan – 2

23rd XAT Scan – 1

19th Sequences -16

18th Sequences – 15

17th Sequences – 14

16th Sequences – 13

12th Sequences – 12

11th Sequences – 11

10th Sequences – 10

9th Sequences – 9

7th Quant 5 – The Number Line Problem

5th Sequences – 8

4th Sequences – 7

3rd Sequences – 6

2nd Sequences – 5


28th Sequences  – 4

27th Sequences  – 3

26th Sequences – 2

25th Sequences – 1

21st Last Digits – 4

20th Last Digits – 3

19th Last Digits – 2

18th Last Digits – 1

14th Pigeonhole Principle -4

13th Pigeonhole Principle – 3

12th Pigeonhole Principle -2

11th Pigeonhole Principle – 1

7th Circles Plotting 3

6th Circles Plotting 2

5th Circles Plotting 1

4th Modulus Plotting – CAT Scan

2nd Quant 4 – When to Avoid the Venn


31st Modulus Examples – 2

30th Modulus Examples – 1

29th Modulus Functions in Two Variables – 6

28th Modulus Functions in Two Variables – 5

26th Quant 3 – Looking from the Other Side

24th Modulus Functions in Two Variables – 4

23rd Modulus Functions in Two Variables – 3

22nd Modulus Functions in Two Variables – 2

21st Modulus Functions in Two Variables – 1

19th Quant 2 – Concepts, not Formulae

17th Modulus Addition – 4

16th Modulus Addition – 3

15th Modulus Addition – 2

14th Modulus Addition – 1

12th Quant 1 – Approximation

10th Modulus Plotting – 4 (Maxima and Minima)

9th Modulus Plotting – 3

8th Modulus Plotting – 2

7th Modulus Plotting – 1

5th Logic Over Formulae

3rd Frustum – Applied Similarity

2nd The Truncated Cone – The Frustum

1st Similarity in Cones


30th Similarity in 3-D

28th DS – Weighted Averages

26th Shortest Path – Cuboid

25th Shortest Path – Cylinder

24th Cubes and Cubelets – 2

23rd Cubes and Cubelets – 1

19th Triangles – CAT Scan 4

18th Triangles – CAT Scan 3

17th Triangles – CAT Scan 2

16th Triangles – CAT Scan 1

14th GMAT – Probability 1

12th Spotting Similarity and Congruence

11th Debunking the Angle-Side-Side Test

10th Triangles – Similarity and Congruence

9th Similarity and Congruence

7th Data Sufficiency – 2

5th Triangles – Examples 8

4th Triangles – Examples 7

3rd Triangles – Examples 6

2nd Triangles – Examples 5


31st Data Sufficiency – 1

29th Fibonacci in Geometry – some examples

28th Fibonacci in Geometry

27th The Golden Ratio

26th The Fibonacci Sequence

22nd Triangles – Examples 4

21st Triangles – Examples 3

20th Triangles – Examples 2

19th Triangles – Examples 1

15th Some thoughts on Inradii and Circumradii

14th Triangles – Area Formulae

13th Some more useful triangles

12th Some useful triangles

10th Data Sufficiency – 0

8th The Angle Bisector Theorem

7th The Theorem of Apollonius

6th The Basic Proportionality Theorem

5th Some Points to Note

1st The Incentre


31st The Circumcentre

30th The Centroid

29th The Orthocentre

25th Writer’s Block – CAT Scan 4

24th Writer’s Block – CAT Scan 3

23rd Writer’s Block – CAT Scan 2

22nd Writer’s Block – CAT Scan 1

18th Singles – 8

17th Singles – 7

16th Singles – 6

15th Singles – 5

11th Singles – 4

10th Singles – 3

9th Singles – 2

8th Singles – 1

4th Unwrite – 4

3rd Unwrite – 3

2nd Unwrite – 2

1st Unwrite – 1


27th Writer’s Block – 8

26th Writer’s Block – 7

25th Writer’s Block – 6

24th Writer’s Block – 5

20th Writer’s Block – 4

19th Writer’s block – 3

18th Writer’s Block – 2

17th Writer’s Block – 1

13th Base Systems – Examples

12th Some Basic Tricks

11th Base Systems – Properties

10th Base Systems- Introduction

6th PnC Round-up

5th The Multinomial Theorem

4th Theory of Partitioning – CAT Scan

3rd PnC CAT Scan – 2


30th PnC CAT Scan – 1

29th The Necklace Problem

28th Derangements – 2

27th Derangements – Introduction

23rd Rings and Fingers

22nd Distinct Objects in Identical Groups

21st Identical Objects in Identical Groups

20th Distribution with Upper Limits on Group Size

16th Distribution of Some or All Objects, Distinct Groups

15th Partitioning – Some Examples

14th Theory of Partitioning 2 (No Groups Empty)

13th Theory of Partitioning 1 (Groups may be Empty)

9th Inscribed Angle Theorem – CAT Scan

8th Inscribed Angle Theorem – Applications

7th Circles and Quadrilaterals

6th The Inscribed Angle Theorem

2nd Trapezium – Examples 2

1st Trapezium – Examples


30th An interesting property of the Trapezium

29th The Trapezium

25th PnC Examples 7

24th PnC Examples 6

23rd PnC Examples 5

22nd PnC Examples 4

18th Pnc Examples 3

17th PnC Examples 2

16th PnC Examples 1

15th Arranging Fussy People

11th To Permute or to Combine?

10th Combinations

9th Forming Numbers

8th Forming Words

4th Sending distinct objects to distinct groups

3rd Permutations – Variants

2nd Permutations

1st Arrangements with some objects identical


28th Variant Arrangements

27th Basic Linear and Circular Arrangements

26th FPC – Examples

25th The Fundamental Principle of Counting

21st The Chinese Remainder Theorem

20th Fermat’s Little Theorem

19th Remainders with Specific Divisors

18th Remainders and the Binomial Theorem

14th Pascal’s Triangle – Examples

13th Pascal’s Triangle and Combinations

12th Pascal’s Triangle – Introduction

11th The Binomial Theorem

7th Applying Negative Remainders

6th Negative Remainders

5th Remainders of powers

4th Remainders of Sums and Products


28th Remainders – 4

27th Remainders – 3

26th Remainders – 2

25th Remainders – 1

21st Multiplication – 2

20th Multiplication – 1

19th Shortest Path – CAT Scan

18th Shortest Path 5

14th Shortest Path 4

13th Shortest Path 3

12th Shortest Path 2

11th Shortest Path 1

7th Escalators – 2

6th Escalators – 1

5th TSD – 2

4th TSD – 1


31st Sum of Factors

30th Number of Factors

29th Fixed and Variable Costs – 2

28th Fixed and Variable Costs – 1

24th Weighted Averages – CAT Scan

23rd Weighted Averages – 3

22nd Weighted Averages – 2

21st Weighted Averages – 1

17th The Square Root Function

16th Recursive Expressions 2

15th Recursive Expressions 1

14th Logical puzzle

57 thoughts on “Maths Posts

    • Will try Yash, but chances are till CAT is done and dusted my life is going to be rather packed 😀 It’s only a month’s worth of posts that is not updated anyway…


    • We will, Harsh. But slowly 🙂 From next week we are going to dramatically slow down the flow of posts…so that we authors can get back to having a life 😉


  1. hii sir

    can u please post few problems on the application of number system, ordered unordered pairs and anything that u think might help us

    i must say sir the way u explain or provide logic is very effective and easy to grasp

  2. Sir can we have posts on maximizing and minimizing in set theory and few quality questions on functions and graphs,that would be very very helpful.Thanks again 🙂

  3. Hello Sir, Would be great if you could upload an article where area and volume of 3D figures like Pyramid, Prisms, tetrahedron etc are derived.. Thank you ☺️

  4. A Russian luxury pen maker sells ‘x’ pens to a supermarket called Large Bazaar at a total price of Rs.(100 + 120x). If the Large Bazaar sells all the pens at a total price of Rs. 3×2, find the maximum loss (in Rs.) that could have been incurred by the Large Bazaar.

    what could be other method to find mxm loss without using double diffrentiation.

      • Let x be 1, then the bazaar bought a pen at a price of Rs. 220 and sells it at 312 which profits the bazaar. As the number of pens increase the profit decreases. The maximum value of x can be 9. For 9 pens the cost price will be 100+120*9 = 1180. Selling price is 392. So 1180 -392=788 which is the maximum possible loss.

    • Let x be 1 then cost price = 220 Selling price = 312 which profits the bazaar. As the value of x increases the profits decreases. The maximum value of x can be 9.
      So Cost price = 100+ 120*9 = 1180. Selling price = 392. maximum loss = 1180 – 392 = 788

  5. Noticed that some of the probability articles (19-28) do not show up on the list of “Maths Posts”, but while going through the individual topics, those appear in the “Next Article”/”Previous Article” link. Could you please add the links for these to the list?

    • Probably not, for two reasons: firstly, I haven’t seen those ever coming in CAT, and secondly, I solve them slowly and painfully when I encounter such questions 🙂 I don’t have any particularly useful trick or approach to add. I prefer to post only where I feel I can provide some genuine value-add…


    • What you could do is, go to the “tag cloud” on the right side and pick a topic. You’ll get all the posts which are related to that particular topic. Go down to the last (i.e. earliest) post on that topic and start reading upward from there! Not all topics are comprehensively covered; I have focused on those where I felt I could add some value above and beyond the obvious stuff found in any textbook.


  6. Hi,
    I want to improve my arithmatic skills. Can you please recommend a sequence in which I should go through this blog. Thanks 🙂

    • Gautam, I haven’t really put up that much on Arithmetic; I have focused on the topics where people generally have trouble with the standard approaches (notably Number Theory and Combinatorics). In Arithmetic, you should probably cover the basics from any standard textbook, and then go through the “Paperless” tag in this blog, there you will find a fair number of arithmetic questions with alternative approaches.


    • I am afraid not. Two reasons – one is that I have said most of what I wished to say (where I can add significant value), the second and more crucial is that my health has not permitted it (I’m under doctor’s orders to reduce screen-time if I wish to preserve my eyesight).


  7. Oh, you should take care of yourself. And thanks a lot for all your posts. I have literally downloaded all of them and made pdfs so that they are handy everywhere. 😀

  8. Hello Sir, I am just starting for CAT’17 with almost 140 days remaining. Where to start from your blog please guide me.There are lots of posts. I am confused what to study what not to.

    • First of all understand that this blog (or any other source) will not magically prepare you. It is just a prop to aid you in improving and to offer some different perspectives and approaches for problems. Not every topic is covered in detail, only those where I felt I had some value add to offer over and above the common sources. Having said which, a good place to start might be PnC (go to the “PnC” tag on the right; there would be around 50 posts. Start reading from the bottom, from the Fundamental Principle of counting!). Remainders would be another good place to start. Another possible approach would be to cover some small but useful topics – I would recommend Logs, Last Digits, Coordinate Geometry and maybe Bases as good places to begin here. When you get a bit closer to the exam and some basics are in place, you should visit the “Paperless” tag to get some idea of how one could solve certain problems in a more efficient manner, with minimal writing.


  9. Sir, I had a small query. Does attempting TITA questions wrongly have any effect on my percentile due to less accuracy? (I know I wouldn’t get negative marks for TITA question.)

    • No. None whatsoever. If you get a particular raw score (say 30) in a particular section in a particular slot, you will get the same percentile irrespective of how you arrived at that score (for example “10 correct” or “11 correct 3 wrong” or “10 correct + 5 TITA wrong”)


  10. Sir, Can you let me know if you have a blog on ‘pipes and cisterns’ types of sums? I tried finding them, but couldn’t find them.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s