Tag Archives: logic puzzles

Solution to Puzzle #199: Two-Cube Calendar

Posted on November 19, 2017 by Alok Goyal

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 →

Posted in Solution | Tagged , | Leave a comment

Puzzle #199: Two-Cube Calendar

Posted on October 22, 2017 by Alok Goyal

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 →

Posted in Puzzles | Tagged , | 1 Comment

Solution to Puzzle #196: Bugs on a Board

Posted on October 15, 2017 by Alok Goyal

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 →

Posted in Solution | Tagged , , , | Leave a comment

Solution to Puzzle #195: 1989!

Posted on September 24, 2017 by Alok Goyal

I received many correct answers. These included  Suman 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 →

Posted in Solution | Tagged , , | Leave a comment

Puzzle #196: Bugs on a Board

Posted on September 17, 2017 by Alok Goyal

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 →

Posted in Puzzles | Tagged , , | 1 Comment

Solution to Puzzle #194: Adjacent Cells on a Chessboard

Posted on September 17, 2017 by Alok Goyal

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 →

Posted in Solution | Tagged , | Leave a comment

Puzzle #195: 1989!

Posted on September 10, 2017 by Alok Goyal

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 →

Posted in Puzzles | Tagged , , , | 4 Comments

Puzzle #194: Adjacent Cells On a Chessboard

Posted on September 2, 2017 by Alok Goyal

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 →

Posted in Puzzles | Tagged , , | 1 Comment

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

Posted on August 27, 2017 by Alok Goyal

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 →

Posted in Solution | Tagged , , , | Leave a comment

Solution to Puzzle #190: Escalator Race

Posted on August 20, 2017 by Alok Goyal

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 →

Posted in Solution | Tagged , | Leave a comment