Tag Archives: logic puzzles

Solution to Puzzle #199: Two-Cube Calendar

This puzzle was originally posted in April 1969 by Martin Gardner, and is a classic even today. Thanks for an overwhelming response to the puzzle and my apologies for the delayed post as I was traveling on work outside the … Continue reading

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Puzzle #199: Two-Cube Calendar

Every time you pick up a Martin Gardner book, there is still always a wonderful puzzle that one has not seen. This one is an original Martin Gardner puzzle, i.e. this is his own creation, published in the book The … Continue reading

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Solution to Puzzle #196: Bugs on a Board

Apologies for not posting anything in the last few weeks, was traveling on work or vacation through this period. This was not a very difficult puzzle, but I got correct answers only from the two people who solve every puzzle … Continue reading

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Solution to Puzzle #195: 1989!

I received many correct answers. These included ┬áSuman Saraf, Vishal Poddar and Anand Sanghi. Thank you and well done! This puzzle can be solved using the concept of “invariants” and parity. Note that for any numbers a and b (a … Continue reading

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Puzzle #196: Bugs on a Board

Yet another very fine puzzle from A Moscow Math Circle: Week by Week Problems by Sergey Dorichenko. Each square of a 9 x 9 board has a bug sitting on it. On a signal, each bug crawls onto one of … Continue reading

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Solution to Puzzle #194: Adjacent Cells on a Chessboard

I got only two correct answers for this puzzle – from Suman Saraf and Pratik Poddar – thank you both and well done! I am taking the liberty of copying the answer from Pratik – I find it to be … Continue reading

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Puzzle #195: 1989!

This is a beautiful puzzle from Mathematical Circles (Russian Experience) by Dmitri Fomin, Sergey Genkin and Ilia Itenberg. There numbers 1, 2, 3, ….. , 1989 are written on a blackboard. It is permitted to erase any two of them … Continue reading

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Puzzle #194: Adjacent Cells On a Chessboard

This is another beauty of a puzzle from A Moscow Math Circle: Week by Week Problems by Sergey Dorichenko. The numbers from 1 to 64 have been placed in each square on a chessboard such that each number appears exactly … Continue reading

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Solution to Puzzle #191: 1×4 Rectangular Stone Plates

This was one of my favorite puzzles, though slightly difficult. Unfortunately I got only one correct answer this time, from Suman Saraf. Well done Suman! The answer is “no”. Look at the unusual coloring of the 10×10 board above. Please … Continue reading

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Solution to Puzzle #190: Escalator Race

This was a tricky puzzle – I received two correct answers, one from Prakhar and another one from Suman Saraf. Thank you both! Answer is that they will reach at the same time, provided certain conditions are met, see the … Continue reading

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