Pi(e) photo by Emily Hilliard.
It’s not the loneliest number, but it might be the most famous. Pi (or π) is commonly defined as the ratio of the circumference of a circle to its diameter. π has been calculated to trillions of digits, but most people just know the first few, namely 3.14—hence, Pi Day, celebrated every year on March 14th (3/14, get it?).
If you haven’t already rolled your eyes and closed this tab, you might be the type who’d enjoy reading more about Pi and/or math in general, so here are some librarian recommendations. And don’t forget to enjoy a slice of Pi(e) while you’re at it.
Recommended: Books About Pi
![Book cover for A History of π (pi)](https://www.lapl.org/sites/default/files/styles/staff_recommends_x97w/public/items/2020/tlccontent-1.jpeg?itok=Ea3tRNiv)
![Book cover for π: A Biography of the World's Most Popular Number](https://www.lapl.org/sites/default/files/styles/staff_recommends_x97w/public/items/2020/tlccontent-2.jpeg?itok=QSOJAQmx)
![Book cover for The Joy of π](https://www.lapl.org/sites/default/files/styles/staff_recommends_x97w/public/items/2020/tlccontent_0.jpeg?itok=kR9aZirE)
Recommended: Books About Math
![Book cover for The Man Who Knew Infinity: A Life of the Genius Ramanujan](https://www.lapl.org/sites/default/files/styles/staff_recommends_x97w/public/items/2020/tlccontent-3.jpeg?itok=Mz4H-LE7)
![Book cover for Hidden Figures: The American Dream and the Untold Story of the Black Women Mathematicians Who Helped Win the Space Race](https://www.lapl.org/sites/default/files/styles/staff_recommends_x97w/public/items/2020/tlccontent-4.jpeg?itok=aBe8AK82)
Hidden Figures: The American Dream and the Untold Story of the Black Women Mathematicians Who Helped Win the Space Race
![Book cover for Cryptonomicon](https://www.lapl.org/sites/default/files/styles/staff_recommends_x97w/public/items/2020/tlccontent-5.jpeg?itok=sG7jrqDm)
![Book cover for Everything and More: A Compact History of Infinity](https://www.lapl.org/sites/default/files/styles/staff_recommends_x97w/public/items/2020/tlccontent-6.jpeg?itok=RHx4caAV)
![Book cover for A Beautiful Mind](https://www.lapl.org/sites/default/files/styles/staff_recommends_x97w/public/items/2020/tlccontent-7.jpeg?itok=MOFNDyVW)
![Book cover for Women in Mathematics](https://www.lapl.org/sites/default/files/styles/staff_recommends_x97w/public/items/2020/tlccontent-8.jpeg?itok=RrgphgsL)
![Book cover for The Signal and the Noise: Why So Many Predictions Fail—But Some Don't](https://www.lapl.org/sites/default/files/styles/staff_recommends_x97w/public/items/2020/tlccontent-10.jpeg?itok=ECe4PieS)
The Signal and the Noise: Why So Many Predictions Fail—But Some Don't
![Book cover for Weapons of Math Destruction: How Big Data Increases Inequality and Threatens Democracy](https://www.lapl.org/sites/default/files/styles/staff_recommends_x97w/public/items/2020/tlccontent-11_1.jpeg?itok=Dio_cgr-)
Weapons of Math Destruction: How Big Data Increases Inequality and Threatens Democracy
![Book cover for Fermat's Enigma: The Epic Quest to Solve the World's Greatest Mathematical Problem](https://www.lapl.org/sites/default/files/styles/staff_recommends_x97w/public/items/2020/tlccontent-12.jpeg?itok=zjTZ7XrS)
Fermat's Enigma: The Epic Quest to Solve the World's Greatest Mathematical Problem