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Dr. Shapiro's Puzzle of the Day

Today's Puzzle

Monday, November 16
What word connects all these images?
   


     Note: Clicking "Submit" will send your response to Dr. Shapiro.

Yesterday's Puzzle + Solution

Today I have a bit of geography trivia for you (and I do mean trivial). Graduates of Dr. V's geography mini-course, come to the white courtesy phone.

Five pairs of countries are highlighted on the map at left. What's special about these five pairs (and no other country pairs in the world)?

Bonus Question (STILL OPEN) And just to make everything about the U. S. (with apologies to my international reader(s)), which two pairs of U. S. states are like these pairs of countries?

Solution The country pairs are Iran/Iraq, Niger/Nigeria, Zambia/Zimbabwe, Central African Republic/Chad, and Guinea/Guinea-Bissau. These pairs of countries "border" each other in two ways; they are geographically adjacent, but also appear consecutively when all the world's countries are listed in alphabetic order!

Now that you know that, feel free to take another crack at the bonus U. S. state question; I'll leave it open for another day and recognize the solvers tomorrow.

This was a tough one. A lot of you got close, but only Jacob C. and Maddy solved it. Congratulations, you two, and 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 to June 2020.