# What is Pi Day? What you need to know about the holiday celebrating an iconic mathematical symbol

Thursday marked National Pi Day in the United States and around the world. The holiday commemorates a timeless symbol beloved by many math and science communities, while making the most of the opportunities it provides for humorous puns, desserts, and “teachable moments,” as the saying goes. some. experts said.

## What is pi?

Pi is a special number – so special, in fact, that most laypeople are probably aware of it, if only as a relic from lectures or geometry textbooks of the past. Represented in abbreviated form by the somewhat familiar sequence 3.14, pi, or the Greek letter π, is an iconic symbol found in mathematical equations and, in recent decades, in products such as T-shirts, sweatshirts, shirts and coffee mugs.

It is actually a ratio designating the relationship between the circumference and the diameter of a circle. If the outline of a circle is drawn, unrolled and then measured, the length is called its circumference. The length of a line passing directly through the center of a circle and extending to its edges is called the diameter. Dividing the circumference by the diameter of all the circles will give you the same result: pi – and this is true for all circles, regardless of their size.

Pi is a constant or “universal” number, that is, a value that does not change regardless of circumstances. This means that π is always equal to 3.14, more or less. After these three famous numbers comes an endless “irrational” sequence, without permanent patterns or repetitive sections. Even though the sequence continues indefinitely, a hobby of pi enthusiasts is to memorize and recite as many decimal places as possible. The Guinness World Record is 70,000.

## Why is pi important?

This report is popular among math and science enthusiasts for a reason: Pi performs essential functions in many of the most basic and complex equations. It is necessary to calculate the area and volume of everything circular and spherical, and this allows humans to measure the size of small things, like molecules, in the same way that it allows them to estimate the size of massive things, like the Earth, the moon. , the other planets and the sun. Pi helps NASA engineers build a spaceship just as it helps scientists study newly discovered worlds. It is also fundamentally linked to gravity.

Manil Suri, professor of mathematics and statistics at the University of Maryland, Baltimore County, said pi helps people better understand the world, the universe and how they work.

“It's quite amazing that there is such a constant that is true for all circles. That's what really appeals to me. Draw any circle and the circumference divided by the diameter will always be the same number. It’s a little scary in a way,” Suri said. “I think symbolically it just shows that there are certain laws that the universe follows, and these are mathematical, and for me as a mathematician, that's the key. Whether we measure in meters or feet or whatever, whether we exist or not, that number will always be the same. That's the kind of amazing thing.”

Pi appears frequently and often unexpectedly in the answers to “thousands and thousands of different math problems,” said Daniel Ullman, a mathematics professor at George Washington University, who also called pi “an incredible curiosity.”

“My preferred point of view is not to ask the question, 'Why is pi important?' » Because I can try to explain why the number six is important, but it's just another number. Pi is just the name of a particular place on the number line,” Ullman said.

“The real question is, 'Isn't it amazing that this number occurs in millions of different contexts that seem to have nothing to do with each other?'” he said . “You ask a reasonable question, and the answer turns out to be something with a pi. It's the surprising appearance of that same number over and over again that makes it interesting.”

## What is Pi Day?

Pi Day is celebrated every year on March 14, since the date written numerically corresponds to the first three digits of π. (Pi Day was particularly notable in 2015, when the digital date matched π up to five digits: 3.1415.) It's also coincidentally Albert Einstein's birthday.

People and civilizations have known about Pi for thousands of years, and evidence indicates that an approximate measurement was used by the ancient Babylonians and ancient Egyptians. The first calculation of pi was made by Archimedes, a legendary mathematician of the ancient world, in the centuries before the Common Era.

But this party only came into existence in 1988. It was founded by physicist Larry Shaw, who was then on the staff of the Exploratorium, a science museum in San Francisco. It all started at an Exploratorium staff retreat in Monterey, California, which Shaw and his colleagues celebrated to mark three years since the death of Robert Oppenheimer, founder of the Exploratorium. Shaw made the connection between March 14 and March 14 during this retreat, and the first informal Pi Day was celebrated that same year at the museum for honor the memory of Oppenheimer.

Pi Day became a recognized national day in the United States decades later, thanks to a binding resolution passed by the House of Representatives on March 12, 2009, designating March 14 as National Pi Day.

## How to celebrate Pi Day

As an official Pi Day website suggests, eating pie, baking pie, and perhaps observing the mathematical principles of pi using a pie are some themed activities to enjoy. Pizza and dessert pies are both suitable variations. A play on traditional “pie contests,” pi contests are common on Pi Day and often involve competitions to recite as many digits of π as possible from memory.

But there's no right or wrong way to celebrate Pi Day. For people around the world excited about the mathematical meaning of pi and the wide potential for honorific puns related to it, there are many ways to pay homage. The same goes for educators and students, although math and science experts generally recommend using Pi Day festivities as opportunities to make learning more fun. The Children's Museum of Houston, for example, will celebrate the holiday with its 14th Annual Pie Fightinviting children to throw shaving cream pies at each other in a cordoned off section of the street.

Math fans recognize that typical Pi Day celebrations have little to do with the mathematical constant. However, Suri would still encourage educators to take full advantage of the fun holiday and always bring pie to class when teaching on Pi Day.

“Every time I have a lecture on Pi Day, this is the way to go,” he said. “And I would recommend it to all teachers. Buy a pie. People will love it. They will listen to your lessons much more attentively.”