Category Archives: Puzzles

Puzzle #79: Diwali Special

Posted on October 26, 2014 by Alok Goyal

Since playing cards is very popular during the Diwali festival, here is a special probability puzzle with cards, contributed by Alok Mittal from his Mathematical Circles class. I heard this one last night and could not resist. I am breaking … Continue reading →

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Puzzle #78: Probability of #6

Posted on October 18, 2014 by Alok Goyal

This is a wonderful probability puzzle given to me by my nephew, Karan Sharma, who lives in Jaipur and is in Class XII – thanks Karan! A man is known to speak the truth 3 out of 4 times. He … Continue reading →

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Puzzle #77: Make the Stacks Equal

Posted on October 4, 2014 by Alok Goyal

Another beautiful puzzle from the same book as last time…”Mathematical Circle Diaries, Year 1″, by Anna Burago. This one is the last puzzle from Session 10. Six stacks of coins are places on the table. The first has 1 coin, … Continue reading →

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Puzzle #76: What’s The Final Digit?

Posted on September 27, 2014 by Alok Goyal

A beautiful puzzle for ages 10-100! Found this in Mathematical Circle Diaries, Year 1 (for grade 5-7), Session 25, problem #8. Robby the Robot multiplied the numbers from 1 to 100 (100 factorial) and calculated the sum of the digits … Continue reading →

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Puzzle #75: Clock Reflection

Posted on September 21, 2014 by Alok Goyal

Here is a nice clock problem I found on a web site, originally created by Lewis Carroll. A clock has hour and minute hands of the same length and no numerals on its face. At what time between 6 and … Continue reading →

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Puzzle #74: Overlapping Clock Hands

Posted on September 7, 2014 by Alok Goyal

This is a relatively simple puzzle, more geared for children than for adults. My friend Alok Mittal recently asked this question in his Mathematical Circles class and also reminded me that he was asked this puzzle (probably 30 years back!) … Continue reading →

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Puzzle #73: Find The Two Numbers

Posted on August 30, 2014 by Alok Goyal

This is a beautiful puzzle that came to me through an IITD friend (Sirisha), and I had not done before – thank you Sirisha! There are two friends A and B. Their teacher calls them separately and tells A, the … Continue reading →

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Puzzle #72: Who Lies?

Posted on August 23, 2014 by Alok Goyal

This is a simple puzzle, hopefully the younger ones will like it too. I got inspired by this puzzle through Alok Mittal’s last Mathematical Circles class on “truth tellers and liars”. This puzzle is taken from Martin Gardner’s “The Colossal … Continue reading →

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Puzzle #71: May the Fastest Horses Win

Posted on August 9, 2014 by Alok Goyal

A beautiful puzzle, initially given to me by a close friend – Naresh Kumra, while trekking to the Everest Base Camp two years back. Came across this again last week in MindCipher. The London racetrack needs to submit its top … Continue reading →

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Puzzle #70: Equal Heads (Outstanding Puzzle!)

Posted on August 2, 2014 by Alok Goyal

This one is one of the best puzzles I have come across in recent times…contributed by Vardhan Rajkumar based out of London. I do not know the original source of the puzzle. No special knowledge or skill required, so suitable … Continue reading →

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