Author Archives: Alok Goyal

Solution to Puzzle #105: The 150 Year Old Puzzle

Posted on July 11, 2015 by Alok Goyal

This was indeed a more difficult puzzle than it appeared and for a change I did not get any correct solution. One realises that after trying a few combinations for the first 2-3 days, one invariably gets stuck in a … Continue reading →

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Puzzle #105: 150 Year Old Puzzle

Posted on July 4, 2015 by Alok Goyal

This is truly an old puzzle. I was sent this one by Salik Shah (thank you Salik). It appeared in the WIRED magazine. I am reproducing the puzzle verbatim as I saw it in WIRED: IN 1850, THE Reverend Thomas … Continue reading →

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Solution to Puzzle #104: Togglers Puzzle

Posted on July 4, 2015 by Alok Goyal

Apologies for an inordinate delay in posting the answer to this puzzle. I was on vacation with children over the last 3 weekends 🙂 This was a very interesting, though a slightly difficult puzzle. I got 4 correct answers from … Continue reading →

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Puzzle #104: Togglers Puzzle

Posted on June 7, 2015 by Alok Goyal

Another beautiful puzzle this time – one from my nephew Karan Sharma, originally seen from Khan Academy, though available at other places as well. This is a truth-liar problem. Here it goes: You are in a room with five people. … Continue reading →

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Solution to Puzzle #103: Proof Without Trigonometry

Posted on June 7, 2015 by Alok Goyal

A wonderful puzzle, and the solution is a beautiful one. This was a difficult one, and therefore I did not get as many answers to the puzzle. Abhinav was the first one to send a correct answer – and a … Continue reading →

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Puzzle #103: Proof Without Trigonometry

Posted on May 30, 2015 by Alok Goyal

This is a wonderful puzzle I found in the puzzle collection of The Guardian newspaper, the original source being Martin Gardner. The beauty of this puzzle is that one needs to use simple rules of geometry and we do not … Continue reading →

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Solution to Puzzle #102: The Persistence Problem

Posted on May 30, 2015 by Alok Goyal

This was a difficult puzzle, though I continue to be amazed how so many people solve them with such speed…my hats off to all the ones who solved this one. That includes Saurabh Aggarwal, Abhinav Jain, Akshay Joshi, Suman Saraf … Continue reading →

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Puzzle #102: The Persistence Puzzle

Posted on May 24, 2015 by Alok Goyal

This is yet another famous puzzle from the Martin Gardner collection. I was made aware of this one by my nephew, Karan Sharma – thank you! I have not looked up the answer to this one, so do not know … Continue reading →

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Solution to Puzzle #101: Shortest Path Touching the X-axis

Posted on May 24, 2015 by Alok Goyal

Thanks to Arunima and Amol again for contributing a wonderful puzzle. This is a famous puzzle called the Heron’s Shortest Distance Problem and has historical roots. The puzzle can be solved through calculus, but can be solved without any calculus … Continue reading →

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Puzzle #101: Shortest Path Touching the X-Axis…

Posted on May 17, 2015 by Alok Goyal

This is a beautiful puzzle initially sent to me a month back by Arunima, a friend from IIT Delhi now in Washington DC. The same puzzle was sent to me by another friend’s son, Amol Aggarwal, now doing his PhD … Continue reading →

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