Researchers using supercomputers have figured out that any scrambled Rubik’s Cube can be completely solved in no more than 20 moves. (And I’m happy to report that one of the people involved, who is quoted in the linked article, is a mathematician at Kent State University, here in Ohio.) Why were supercomputers needed, you ask? Because Rubik’s Cubes can be put into 43 billion billion different starting positions. The vast majority of these can be solved within 15 to 19 moves. In 100 million combinations, exactly 20 moves are needed to solve the puzzle.
20 moves! Just what I needed: something else to remind me that I was clueless when it came to figuring out a Rubik’s Cube, or one of those bent nails puzzles.
I had a friend once who got so frustrated with the apparently unsolvable Rubik’s Cube that he steamed the colored squares off the plastic underneath and re-glued them so that he could brag to friends that he figured it out. Of course, he might have done better if he’d been helped by a supercomputer or two.