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

A History of π (pi)

Petr Beckman

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π: A Biography of the World's Most Popular Number

Alfred S. Posamentier

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The Joy of π

David Blatner

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Recommended: Books About Math

The Man Who Knew Infinity: A Life of the Genius Ramanujan

Robert, Kanigel

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Hidden Figures: The American Dream and the Untold Story of the Black Women Mathematicians Who Helped Win the Space Race

Margot Lee Shetterly

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Cryptonomicon

Neal Stephenson

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Everything and More: A Compact History of Infinity

David Foster Wallace

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A Beautiful Mind

Sylvia Nasar

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Women in Mathematics

Lynn M. Osen

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The Signal and the Noise: Why So Many Predictions Fail—But Some Don't

Nate Silver

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Weapons of Math Destruction: How Big Data Increases Inequality and Threatens Democracy

Cathy O'Neil

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Fermat's Enigma: The Epic Quest to Solve the World's Greatest Mathematical Problem

Simon Singh

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