It’s great to see that Ponder This has reached its 127th month. I love these monthly challenges which I first discovered in November 2002. After many years, it got me interested again in doing Maths puzzles, particularly those related to combinatorics. Over the last couple of years the puzzles have moved more towards probability problems… this is a subject that I didn’t enjoy at all as an undergraduate, and in an attempt to improve myself I have been working though 50 Challenging Problems in Probability This was a really enjoyable read. It includes such gems as the coupon collection puzzle (if a free gift comes with a breakfast cereal and there are n to collect, how many boxes will I need to buy), how long on average to draw an ace from a pack of cards, if I lay two packs of cards side-by-side how many matches will I find and the dowry problem (100 pieces of paper with an amount on them drawn one by one – what’s the strategy for stopping on the largest) together with many other interesting problems. One other book of such problems is Peter Winkler’s Mathematical Puzzles: A Connoisseur’s Collection which is also a really good read.