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Celebrating Pi (or even Pie) Day

By Shrina Dong '24



Every year on March 14th, the world celebrates Pi Day. No, not pie; although it is a delicious part of the day that celebrates the iconic mathematical constant denoted by the Greek letter, π.

What exactly is π? π is an irrational number, meaning it goes on for infinity and has no repeating pattern; it’s best known for its first three digits, 3.14, hence why we celebrate it on March 14th (3/14) annually, but it actually took years for mathematicians just to get that approximation. Early calculations largely used measurements, but it was Archimedes, a Greek mathematician, in 200 BC that first used an algorithmic approach to calculate pi. He drew a polygon inside a circle, and as he increased the number of sides, he observed that the shape inside the polygon resembled the circumference of a circle more and more. When he reached a 96-sided polygon, he proved that 2237 < π < 227. Because all circles are similar, the value of π is always the ratio of a circle’s circumference to its diameter. (2πr/2r = π or πd/d = π)

Now with advancements in technology, π was calculated to a record-breaking 62.8 trillion decimal places using a supercomputer, the calculation taking 108 days and nine hours.

Because pi and pie are homophones in English, meaning they have the same pronunciations, and pie resembles a circle, many people celebrate π Day by eating or baking pies. It is also common to hold π reciting competitions, where people recite the most digits of π they can.

Author of Nature and History of Pi, William L. Schaaf says, “Probably no symbol in mathematics has evoked as much mystery, romanticism, misconception and human interest as the number pi.” Although we now know a lot more about pi than when this book was written in 1967, our interests haven’t stopped as we celebrate this mathematical holiday, whether it’s through pi-reciting competitions at school or grabbing a piece of pi(e) at Petee’s Pie Company in the Lower East Side.


Fun Facts:

  • Albert Einstein was born on March 14th, 1879.

  • Larry Shaw is known as the Prince of Pi because he founded Pi Day at San Francisco’s Exploratorium, a science museum he worked at.

  • Pi Day wasn't celebrated in the US until Congress passed Resolution 224, designating March 14th as Pi Day, in hopes that it would create more enthusiasm for math and science among American students.

  • Rajveer Meena recited the most decimal places of π — 70,000 — taking nearly ten hours while he was blindfolded.

Pi used to be referred to as “the quantity which when the diameter is multiplied by it, yields the circumference” and of course people got tired, so the Welsh mathematician William Jones began using π to symbolize pi in 1706.

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