Tag Archives: combinatorial puzzles

Solution to Puzzle #197: 10 Friends

Posted on October 22, 2017 by Alok Goyal

This was a relatively simple puzzle, and I got correct answers from Suman Saraf, Mohit Khare, Vishal Poddar and Pratik Poddar – thank you all! The answer is 1024. An easy way to think about this is to create a … Continue reading →

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Puzzle #197: 10 Friends

Posted on September 24, 2017 by Alok Goyal

This is a very common puzzle, many variants of which one would have. I still like it as the answer is very elegant, and teaches children a methodology. This one is from Mathematical Circles (Russian Experience) by Dmitri Fomin, Sergey … Continue reading →

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Solution to Puzzle #177: How Many Times Can You Measure

Posted on May 7, 2017 by Alok Goyal

This was a difficult puzzle. I got the correct answer only from Suman Saraf, and another correct answer to a slightly modified puzzle from Pratik Poddar. You can measure 23 different lengths. Here’s an explanation, taken from the site fivethrityeight.com. The … Continue reading →

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Puzzle #177: How Many Times You Can Measure

Posted on April 23, 2017 by Alok Goyal

This is a variation of Puzzle #14 (https://alokgoyal1971.com/2013/04/28/puzzle-14-measuring-time/) that I found on the site fivethirtyeight.com. A fantastic puzzle! Suppose you have four ropes and a lighter. Each rope burns at a non-constant rate but takes exactly one hour to burn … Continue reading →

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Solution to Puzzle #168: Who Gets the Easter Eggs?

Posted on February 12, 2017 by Alok Goyal

This was a very counterintuitive puzzle, and a relatively difficult one, though one does not need to know any specific mathematical construct for it. Only two people (father – daughter pair) got the correct answer – Mahi and Suman Saraf! … Continue reading →

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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 #95: How Many Ways to Play the Tabla

Posted on March 15, 2015 by Alok Goyal

Thanks for a record breaking viewership this week…this is the maximum traffic I have had on the site ever since I started the puzzle! Many people sent the correct answer (which is 34 ways to do it). Some people gave … Continue reading →

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Puzzle #95: How Many Ways to Play the Tabla

Posted on March 8, 2015 by Alok Goyal

Heard this awesome puzzle yesterday while watching a video of Manjul Bhargava with my children (thanks to my wife Pooja to introduce me to this one). For those who do not know, Manjul Bhargava is a Princeton Professor who got … Continue reading →

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Solution to Puzzle #86: Add The Digits and Count

Posted on December 31, 2014 by Alok Goyal

This was a difficult puzzle, and I got only one response and a correct one from Ganesh Ramani, my friend from IITD Comp Science and now in Tokyo – well done! To arrive at the solution, lets begin with Variation … Continue reading →

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