Notes to Myself



Puzzle of The Week

Very interesting puzzle! On 3 occasions I thought I found the answer…and then found a better solution. Hope I’ve finally got it right…

Source: A puzzle group on internet


7 Geometry Puzzles

Pink shaded region in above square is what % of area of the square?

Hint: You do not have to know the side of the square to solve this.


The four circles represent cinder paths. The four cyclists started at noon. Each person rode round a different circle, one at the rate of six miles an hour, another at the rate of nine miles an hour, another at the rate of twelve miles an hour, and the fourth at the rate of fifteen miles an hour. They agreed to ride until all met at the center, from which they started, for the fourth time. The distance round each circle was exactly one-third of a mile. When did they finish their ride?

Cyclists Puzzle

Three Puzzles on “2018”

Here are three puzzles related to “2018”. Interesting ones with varying difficulty. Do try and post answers

Remembering Shakuntala Devi

Today is 88th birth anniversary of mathematics wizard Shakuntala Devi, known as the “Human Calculator”.

Google created a Doodle on her 84th birthday to honour her…

As a child the only source of Mathematical puzzles for me were the books by Shakuntala Devi (before I discovered Martin Gardner, Sam Lloyd and W. Sawyer, Alex Bellos et al).

Fields Medal winning American mathematician of Indian origin, Manjul Bhargava explained in one of his talks the difference between math savant and a math genius. By his definition Shakuntala Devi would be called more of a Math savant, and not math genius; nevertheless she is very popular and inspiring person for lot of young students who love mathematics.


The Joy of Solving Brain Teasers, Puzzles and Donald Trump!

I like solving puzzles, brain teasers. That doesn’t mean I am an expert at solving them. It just means that I enjoy the process and I don’t get fed up with trying. And if I get the answer right, that’s a bonus!

Mathematicians often use word “elegant” when they talk about their research or work. By elegant they mean that a complex mathematical equation that looks so simple and yet profound, and that which looks succinct – more like poetry.

Sometimes the answer is not elegant, but the method or arriving at it is. And sometimes the answer itself is so revealing that it evokes another interesting chain of thoughts! I am often in awe of people who compose such puzzles, brain teasers!

Recently I came across this puzzle. Isn’t it wonderful that someone could actually create a puzzle out of nowhere?

And if you think that the puzzle is a genius, you would be amazed once you see the possible solution! The possibility (that the answer proposes) is a frightening thought – sure to spark HUGE debate in the US! See if you can crack that J

If you have missed the clue, it is right there in the title of this blog!


Source: Twitter

3 Locks Puzzle

3 Locks Puzzle

I have a safe with three keycard locks. That is, each lock is like a hotel door lock where you insert a card to operate the lock. I have three cards that look identical, a correct card for each of the locks.

The safe operates as follows.

If only one or two of the cards are inserted into the locks, nothing happens.

If all three cards are inserted, then:
(a) a card in the wrong spot closes the lock;
(b) a card in the correct spot changes the status of the lock: if the lock was closed it becomes open, if it was open, it becomes closed.

The safe only opens when all three locks are open.

This morning I found out that my son played with the cards and the safe.

Now the safe is closed, but I don't know which locks are open or closed, and I can't tell any of the cards from one another.

I'm in a bit of a tight spot. Can I eventually open the safe?

Sinquefield Cup 2017: An epic chess battle and a “Puzzle” (?)

Sinquefield Cup 2017 is progressing well and taking interesting twists and turns! Here is an analysis video of an epic chess battle between Magnus Carlsen and Maxime Vachier-Lagrave (aka MVL).


The game was equal for most of the part, and yet ultimately Carlsen ended up losing it! Check subtle traps and strategies explained by GM Jan Gustafsson


Interestingly MVL was a second (teammate, helper, practice partner) to Magnus Carlsen!


Here is some food for thought – a sort of puzzle. Below is a photo of score-sheets of game between Peter Svidler and Vishwanathan Anand in Round 2. One is written by Svidler and the other of course is written by Anand.


Can you figure out who has written which one?


You just need to know basics of chess score-sheet and how a game/tournament happens. You can guess the answer based on some close investigation and logical deduction. Of course, you can nail the answer if you know more details about chess notation.


Interestingly, you can also guess the answer if you know Anand’s personality and something about Handwriting Analysis.

OK, so here’s the answer.


The left one is written by Peter Svidler and the right one (neat and clean) is written by Vishy Anand.


Here are three reasons:

  1. When you play a game and write a score-sheet; and when the game ends you sign at the bottom against your side (color). Anand played with black and would have signed on right hand side (in both score-sheets). So having his sign on  right hand side doesn’t say much. However, what says a lot, is the fact that he would have signed first on his own score-sheet and then exchanged with Svidler (that is how it happens in an actual game). So you can see the Anand must have written the score-sheet on right hand side, signed it immediately. (hence his sign is immediately below the last move, and Svidler’s is below, on left hand side). Similarly Svidler would have signed immediately below the last move in left hand side score-sheet and then handed over to Anand who had to sign below Svilder’s.
  2. Svidler (left hand side score-sheet) has used Russian style of old notation. Instead of “c2” he wrote “c2-c4”. Similarly he used K for Knight instead of N that is the standard modern notation. Anand (right hand side score sheet), on the other hand has used the modern notation (he wouldn’t use Russian-style notation)
  3. Third and last argument is more based on handwriting analysis/ psychology and is not a strong reason. Anand is very organized and well articulated and thoughtful person. You would expect his handwriting to be neat and clean and not messy like the one on left hand side. The left hand side writing is all over the place; it’s messy and cluttered. Look at the signature. It signature spreads and spills over way far into the other column. Knowing Anand’s personality, you would not expect this kind of handwriting. Of course this is just a hypothesis. But in this case it holds true!


How Usain Bolt Can Break His Own Record…

If Usain Bolt is given this math problem just ahead of race he would run even faster and break his own record!

So don’t doubt if Maths can help in life…

Now go solve the problem!

Olympics Maths

Create a free website or blog at

Up ↑