Working away here, I almost didn’t notice the date: March 14, or 3/14. It’s Pi Day, the offbeat holiday in celebration of our favorite mathematical constant, pi—a.k.a 3.14159, etc. Swiss mathematician Leonhard Euler adopted the symbol, π, in 1737, but the concept has been in use since ancient Greece; it’s also known as Archimedes’ constant. Popular Pi Day activities include eating pie and listening to Kate Bush’s song “Pi,” in which the singer musically recites 137 digits of the constant, leaving out the 79th through 100th decimal places along the way. The song is almost as difficult to listen to as pi is to derive. Here’s a celebratory trivia question: Why was the Greek letter π chosen to represent this important mathematical constant, and who proposed it? I’ll send an issue of Popular Science autographed by the soup vendor outside our office to the first person to answer correctly. (Enter your responses in the "Comments" section below, please.) —Joe Brown
Working away here, I almost didn’t notice the date: March 14, or 3/14. It’s Pi Day, the offbeat holiday in celebration of our favorite mathematical constant, pi—a.k.a 3.14159, etc. Swiss mathematician Leonhard Euler adopted the symbol, π, in 1737, but the concept has been in use since ancient Greece; it’s also known as Archimedes’ constant. Popular Pi Day activities include eating pie and listening to Kate Bush’s song “Pi,” in which the singer musically recites 137 digits of the constant, leaving out the 79th through 100th decimal places along the way. The song is almost as difficult to listen to as pi is to derive. Here’s a celebratory trivia question: Why was the Greek letter π chosen to represent this important mathematical constant, and who proposed it? I’ll send an issue of Popular Science autographed by the soup vendor outside our office to the first person to answer correctly. (Enter your responses in the "Comments" section below, please.) —Joe Brown 
It was first used in 1706 by William Jones. Pi was chosen as the letter to represent the number because the letter [pi] in Greek was pronounced like our letter 'p', and stands for 'perimeter'.
Posted by: Samir | March 14, 2006 at 05:49 PM
I believe it was William Jones, but I always thought it was chosen to symbolize the word periphery.
Posted by: jon | March 14, 2006 at 06:07 PM
Close enough—nice job, Samir. Way to use that Wikipedia. The technically more correct answer is that Pi is the first letter in the Greek word peripheria, which means perimeter. I'll get you that magazine autographed by tommy the soup guy ASAP.
Posted by: PopSci Staff | March 14, 2006 at 06:33 PM
Woops, I mis-typed. As Jon said, peripheria stands for periphery.
Posted by: PopSci Staff | March 14, 2006 at 06:36 PM
Hey Samir—send your address to letters@popsci.com and I will get that autographed issue out to you. —Joe
Posted by: PopSci Staff | March 15, 2006 at 12:52 PM
Anyone got any interesting historical facts about pi that may be useful in a high school classroom?
Posted by: Chris | February 13, 2008 at 08:09 PM
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