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Dr. Shapiro's Puzzle of the Day

Today's Puzzle

Monday, April 26
I recently saw the object at left on someone's desk (with some of the letters lit up). What is it, and what letters are covered by the yellow rectangle?

   


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Yesterday's Puzzle + Solution

Unless you are a circuit engineer, where in daily life are you most likely to encounter the number 4011?

Hint I'm sure you've seen it before; the question is, did the information stick?

Solution You know those little labels on supermarket fruit? The numbers on them are called PLUs (price look-up codes). Long-time cashiers have 'em memorized, and the first one they learn is quite likely 4011, for… bananas.

Friday's eye-watering color scheme was, of course, a hint.

PLUs are mostly the same from store to store, but you might not have had a chance at this if you get your produce at Berkeley Bowl; somehow the cashiers there distinguish hundreds of kinds of produce using inconspicuous colored dots. (And if you get organic bananas, the code on them likely has an extra 9 in front.)

Congratulations to yesterday's solvers Aditi, Andrew I., Trent, and Graham. Thanks to everybody who made a guess!

About This Site

Though he now teaches mathematics, Dr. (né Mr.) Shapiro's first job in a K–12 school was as a lunch monitor in Davis, CA. It was there that he originated the Puzzle of the Day, even rewarding correct answers with tickets in denominations like "15 points" (though without a clear idea of how he'd ultimately redeem these). Dr. Shapiro's favorite puzzle from this pre-professional era was "Tell me the location of the beehive on this campus."

Ten years later, Dr. Shapiro revived Puzzle of the Day at Proof School, writing each day's puzzle on a name tag. After 600 puzzles or so, he was just starting to feel normal about students reading his chest all the time when campus closed and the puzzle, like the rest of our lives, moved online. New puzzles are posted daily on school days.

Want to catch up on old PotDs? There's an archive currently containing puzzles from March 2020 to March 2021.