Can you insert all 10 pennies into the square opening? Looks easy, seems easy, should be easy, but is this an easy puzzle? This is an ideal coffee table puzzle. You do not even have to worry about losing a piece, just a grab a couple pennies from between the couch cushions.
Circle packing is a branch of recreational mathematics where the aim is to pack n unit circles into the smallest possible square. As I thought about it , it occurred to me that this may make a fun puzzle to do with pennies.
The 10 circle problem appeared to be the best challenge, as the solution is not at all obvious. Its precision cut opening is such that the pennies will just fit in with no room to spare. The text is all deeply laser engraved and the backing is heavy duty floorboard so the puzzle has a great weight and feel. The puzzle comes unsolved as there is a temporary home for the tenth penny which you must find a way to insert into the large opening.
The solution is provided.
Level of Difficulty: Level 2