The Australian Mathematical Society Gazettes Puzzle Corner is a regular column with entertaining mathematical puzzles, heres an example: "Triangular trip Assume the Earth is perfectly spherical and you are standing somewhere on its surface. You travel exactly 1 kilometre south, then 1 kilometre east, then 1 kilometre north. Surprisingly, you find yourself back at the starting point. If you are not at the north pole, where can you possibly be?" You can find the Puzzle Corner, as well as the entire Gazette online at: http://www.austms.org.au/Gazette+Volume+38+Number+4+September+2011 Please check it out when you feel like trying out random fun problems, and be sure to send your solutions to us. A $50 book voucher is up for grabs for the best submission, not to mention fame, glory and eternal bragging rights! Entries are judged on the following criteria, in decreasing order of importance: accuracy, elegance, difficulty, and the number of correct solutions submitted. Please e-mail solutions to ivanguo1986@gmail.com or send paper entries to: Kevin White, School of Mathematics and Statistics, University of South Australia, Mawson Lakes SA 5095 The deadline for submission is 1 November 2011. The solutions will appear in the March 2012 issue of the Gazette. Thank you! Ivan Guo