Author Archives: Alok Goyal

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

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

Puzzle #197: 10 Friends

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

Posted in Puzzles | Tagged , | 3 Comments

Solution to Puzzle #195: 1989!

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

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

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!

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

Solution to Puzzle #193: Smallville Telephones

This was a simple puzzle, and I got correct answers from many. These include Vishal Poddar, Pratik Poddar, Suman Saraf, Mahi Saraf and Anand Singhi. Well done all. The answer is “Not Possible”. This is a simple application of graph … Continue reading

Posted in Solution | Tagged , | Leave a comment