Numberplay: The Coins in the Dark Puzzle - The New York Times
Didax Money Sudoku 10 Puzzle Cards & 32 Play Coins For Ages 7 & Up New/Sealed 706406107694 | eBay
Stephen A. Ridley on Twitter: "British coins have a puzzle. The lesser coins form the shield on the back on the one pound (on the left) http://t.co/7sl1uJguUW" / Twitter
10 Coins | Puzzle - YouTube
10 Coins In 3 Cups – Sunday Puzzle – Mind Your Decisions