Pi Day Mar 14, 2022

Pi Day

Did Neolithic humans build this structure to celebrate Pi Day? Not likely. Pi Day is a relatively recent phenomenon—invented by a physicist in 1988 and designated by Congress a national holiday in 2009. But it"s already almost certainly the most popular holiday celebrating a mathematical constant. While Pi Day is a young tradition, the number π (pi) itself has been a fascination since antiquity, when it was first calculated as the ratio of a circle"s circumference to its diameter.

© Guy Edwardes/Minden Pictures

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Today in History

Mar 14, 2018Happy Pi Day!
Mar 14, 2019Rocky mountain pi
Mar 14, 2020A circular celebration
Mar 14, 2021Perfect timing
Mar 14, 2023Pi Day
Mar 14, 2024Happy Pi Day!
Mar 14, 2025Celebrating Pi Day

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