Pi Day: What Is ‘Pi’ And Why Do We Celebrate It?

On March 14 each year we celebrate Pi Day, and we have the physicist Larry Shaw to thank for this as he started the tradition of celebrating Pi Day 29 years ago. Shaw worked with the electronics group at the Exploratorium in San Francisco, and he and his co-workers at the museum were so enthusiastic about pi that they created their own holiday around it on March 14, 1988.

Math enthusiasts will already know what pi is, but for everyone else out there, the official Pi Day website has a succinct explanation of pi.

“Pi is the ratio of a circle’s circumference to its diameter. Pi is a constant number, meaning that for all circles of any size, Pi will be the same. The diameter of a circle is the distance from edge to edge, measuring straight through the center. The circumference of a circle is the distance around.”

A human Pi symbol to celebrate 'Pi Day' in Boston, Massachusetts on March 14, 2017. A human Pi symbol to celebrate ‘Pi Day’ in Boston, Massachusetts on March 14, 2017. [Image by Chitose Suzuki/AP Images]

The number 3.14, or 3.14159 is pi, or π. When you measure objects that are circular, you discover that a circle is just slightly more than three times its width going around.

On Pi Day, we remember the great Greek mathematician Archimedes of Syracuse, who worked out the calculation for pi back in the 3rd century BC. By using polygons with lots of sides that approximated circles, he was able to deduce that pi was roughly 22/7.

Princeton University mathematics professor John Conway said that not long after Archimedes’ time, the world suffered through “a real decline in math,” as Time report.

“Math and science in general went into a great decline from roughly the year zero to the year 1,000, and then the Arabs developed lots of math after that, like trigonometry.”

While techniques for arithmetic were believed to have been in use in India long before the 5th century, Europe was much slower to respond, according to the Mathematical Association of America.

“Even though the Indo-Arabic system, as it is now known, was introduced to Europeans first by Gerbert of Aurillac (c. 946–1003, who became Pope Sylvester II in 999) in the 10th century, and again, in greater detail and more successfully, by Fibonacci in the early 13th century, Europe was slow to adopt it, hampering progress in both science and commerce.”

It is noted on Pi Day that it was William Jones who was the first person to use the Greek letter π for pi in 1706, and the “p” letter stands for the word perimeter when describing the perimeter of a circle. The Greek letter or term for pi, π, became more widely used after Leonhard Euler, Catherine the Great’s Swiss mathematician, began using it in 1737.

Sir Isaac Newton also worked on pi in 1665, recording 16 digits, but later said that he felt bad about how long it took him to work on the computations for pi, as it meant that he was able to conduct “no other business at the time.”

Skip Howell from Raytheon celebrating 'Pi Day' with apple pies on March 14, 2013.

On what happens to also be Albert Einstein’s birthday, people are celebrating Pi Day by, of course, eating pies and wearing hats and fun costumes which are pi-themed. Even the American government is now recognizing this holiday and created National Pi Day on March 14, so that they can give encouragement to “schools and educators to observe the day with appropriate activities that teach students about Pi and engage them about the study of mathematics.”

How are you celebrating Pi Day?

[Featured Image by Marie Callender/Getty Images]