Wordplay, the New York Times Crossword Blog, doesn’t just post info about crossword puzzles. They also run a regular feature on mathematics and logic problems called Numberplay, which is quite fun.

Here’s a puzzle that appeared recently on Numberplay … I didn’t get it, but my 14-year-old son did in just a few minutes:

You are in a room with three switches each of which controls one of three table lamps in a separate room that’s some distance away. The switches are all in the “off” position and have been so overnight, but you know that all three table lamps work. Once you leave the switch room, you can go into the room with the lamps only once. How do you figure out which light switch goes with which table lamp? No tools, helpers or cellphones allowed.

Here’s the solution:

[spoiler /Show Answer/ /Hide Answer/]Turn off switch 1, wait 5 minutes, turn off switch 2, then go into the lamp room. The lamp that is on is controlled by switch 3. Now feel the two bulbs of the off lamps – the hotter of the two off lamps is controlled by switch 2, and the cooler of the two off lamps is controlled by switch 1.[/spoiler]

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Who I Am ePeterso2I’m Eric Peterson, and my email address is I’m a software engineer who lives in a suburb of Fort Lauderdale, Florida. I’ve enjoyed solving puzzles for years, and a few years ago I began constructing puzzles of my own. If you’re ever in Broward County and would like to get together some time, please send me a note by email and let me know. I love the opportunity to meet with other puzzleheads, especially if it involves lunch. Puzzle Testing I believe that the best way to make a puzzle even better is to ask someone else to solve it. You learn so much about how people think, how people approach your puzzle, pitfalls they may encounter, and outright errors in your construction by having someone else try it before you unleash it upon the world. If you’re a puzzle constructor, I would be honored to test your puzzle for you. Send me email with your puzzle or a link to it, and I’ll try solving it, as long as I have time available to do so. I’m a busy guy, so my time is limited … but I’m always open to a challenge. My Public Profiles * My Linked In profile * My profile * My profile Puzzles I’ve Written * Geocaching puzzles Puzzles I’ve Solved * Geocaching puzzles (solved and found) What Happened to ePeterso1? ePeterso1 was a horrible experiment gone wrong that had to be hunted down and killed before he claimed the lives of any more innocent victims. Most of the bugs that caused ePeterso1 to go haywire have been corectted in ePeterso2.

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