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Monthly Archives: September 2017
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
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
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
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
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
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
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
Solution to Puzzle #192: Too Many 6’s
This was a difficult manipulation of numbers, and I received 4 answers from Mahi Saraf, Anand Singhi, Pratik Poddar and Prakhar Prakash. Only two of these I found to be completely correct – from Mahi Saraf and Anad Singhi. That … Continue reading