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Dr. Shapiro's Puzzle of the Day

Today's Puzzle

الخميس ٢٢ أكتوبر
__,١٣,٨,٥,٣,٢,١,١
What comes next?
Answer in the appropriate character set! You can copy and paste from the text above.

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Yesterday's Puzzle + Solution

I'm thinking of two words from mathematics. Both words have appeared (in some form) in the names of Proof School courses. They are anagrams of each other whose last 5 letters are identical. Despite the similarity, they do not share a common root; one is from the Greek for "ratio-number" while the other is named for a 9th-century Persian astronomer (not a former U. S. presidential candidate). What are these words?

Hint These words are also unrelated to a word defined as "a strong, regular, repeated pattern of movement or sound".

Solution The words are logarithm and algorithm. The roots of logarithm can also be seen in the words logic and arithmetic; meanwhile, algorithm is a Latinized form of Al-Khwarizmi, the mathematician–astronomer who taught the Western world how to calculate using Hindu–Arabic numerals.

Thanks to Kate for suggesting the midday addition of an Al Gore reference (the former candidate)! The Hint was referencing rhythm.

Congratulations to yesterday's solvers Zachary Z., Atticus, Anna K., Leo S., Jacob C., Yana, Charlie, Jessica, Kate, 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 to June 2020.