The Australian Mathematical Society Gazettes Puzzle Corner is a regular column with entertaining mathematical puzzles, heres an example: "Counterfeit coins There are 20 coins in front of you, two of which are counterfeits. The genuine coins are identical in weight, but the counterfeits are slightly lighter. Can you identify 10 genuine coins by using a balance-scale twice? Note that the two counterfeits are not necessarily the same weight as each other." You can find the Puzzle Corner, as well as the entire Gazette online at: http://www.austms.org.au/Gazette+Volume+39+Number+1+March+2012 Check it out when you feel like trying out random fun problems, and be sure to send your solutions in. A $50 book voucher is up for grabs for the best submission. 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 May 2012. The solutions will appear in the July 2012 issue of the Gazette. Thank you Ivan Guo