I ran into this puzzle at the last NCTM conference in DC. The company called YMIR Inc. allowed teachers to attempt to solve this puzzle within five minutes. If you were able to solve it, you were able to take it home from free. Great hook, eh? Well, I didn’t solve it there, however I was able to purchase two puzzles for my students to figure out.
Another teacher and myself (as displayed in the picture) was able to solve the puzzle within 10-15 minutes. The goal of the puzzle is to assemble a 16-piece square with all smooth or rough edges.
I was told that there were at least 200 solutions to this puzzle, so what makes it so difficult to solve? There are no pictures on the faces, and the pieces must interlock with no gaps. Great challenge for those students with good perception.
I was also told that this puzzle was created by an Estonian and was brought here to keep us entertained. Good job, homie! Will have to work on lowering my rate of completion. I heard that some people has solved it within five minutes or less. Those folks must really must be mensa certified. Anyway, if you are looking for a challenge, let the ultimate puzzle your next victim.