Archives for Puzzles



A Rental Car Puzzle

Have you ever noticed that whenever you rent a car, when they give you the keys to the vehicle, there are always two sets of keys?  But the two sets of keys are attached to the same key chain, and no matter how hard I’ve tried, I have never figured out a way to detach one set of keys from the other.

What could possibly be the point of giving customers two sets of keys that can’t be separated?  The downside is that if the keys get lost, two sets of keys are gone.  Also, the keys are much bulkier in my pocket than otherwise would be the case.

The only possible explanation I can see is that since no one carries around two attached sets of keys to the vehicle they own, people are less likely to confuse their own car keys with those of the rental vehicle.  It just doesn’t seem like that could be the logic, however.

So can anyone explain to me the real reason rental car companies do this?



The Unusual Suspects: A Good Cryptographer Is Hard to Find

Earlier this year, the structure of an enzyme in an HIV-related monkey virus was solved in three weeks by internet gamers. It was a feel-good victory of human intelligence over disease, and a reminder of the awesome power of the internet.

The New York Times published a similar article a few days ago. In a slightly controversial move, British spy agency Government Communications Headquarters posted a puzzle online and directed people who solved it to apply for a job at GCHQ. It’s reminiscent of the Bruce Willis movie Mercury Rising and seems like an elegant solution to a hiring problem – the GCHQ can’t offer as much money to their cryptographers as private firms. Also, code breaking skills can’t be that easy to find. The Times reports on what happens after you break the code:

“So you did it,” says the congratulatory message. “Now this is where it gets interesting. Could you use your skills and ingenuity to combat terrorism and cyberthreats? As one of our experts, you’ll help protect our nation’s security and the lives of thousands.” Those interested are then invited to submit a formal job application, leading to interviews for a total of 35 jobs next spring.

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A House Puzzler

Here’s a puzzler for people who have seen the latest episode of the TV show House. Read More »



Is Google Making Us Smarter?

It depends on how you use the web, and how you define “smarter.” The internet was abuzz this summer over Nicholas Carr‘s eloquent argument in The Atlantic that the internet is eroding our ability to read long and complex texts (if you agree, but can’t make it through to the end of his 4,200-word essay, […] Read More »



A Little Math Puzzle to Ponder

My good friend Dave Eldan sends me interesting tidbits on a regular basis. More often than not, they are pulled from obituaries. Everyone needs a hobby, I guess. I found his latest missive very interesting. It is from an obituary by Morton White for the great philosopher and mathematician Willard Van Orman Quine. (Unless I […] Read More »