add-a-coin-2 Published 27 December 2016 at 953 × 467 in Forget a new £1 coin, we need a £1.23 coin ← Previous Next → Average number of coins expected as change if you add a new coin of a certain value Jigsaw Jigsaw is a talented chess player and fervent climber. All articles by Jigsaw More from ChalkdustNEW! Pop-math book clubDo you have lots of unread pop math books on your shelves? Join our new monthly online book club!Things to makePlatonic shapes from tube maps, flexagons, and more mathematical craftWhat’s hot and what’s notOptimal Pac-ManGhostbusting with graph theoryReinventing 2DWhat a difference a matrix makesYour social networksHow similar are you to your friends?