December 2017 Problem Of The Month

Money Holder Puzzle

For the past seven years, I have given my nieces their Christmas gift (money) in some kind of a puzzle.  The puzzles are getting more difficult as time progresses.  This year’s puzzle looks like this:

Roughly three inches in diameter.  It is made of metal.  There are two parts visible and the inner part rattles a bit if you shake it and can be rotated within the outer part.

I don’t usually give any hints with the puzzle, but this one I added a little note saying “If you are thinking of prying, banging, impacting, forcing, drilling, or similar, you are on the wrong track.”

So, how does this puzzle open?  But more importantly, what kind of hints should I give my nieces should they be stumped?

I passed several of these out at the meeting and answered questions as the attendees figured it out.


One side of the puzzle is NOT magnetic.

“No” force but gravity required.

Radially symmetric.

Easy to open, but difficult to open quickly.

“cold hard” cash.

John Harrison (1700’s clockmaker)




Triangle Embedded Interest Group