Pi Day

What Is Pi Day?

Every year on March 14th, the world celebrates "Pi Day," named for the approximate value of pi, 3.14. The celebration began in 1988, when American physicist Larry Shaw celebrated the day at the Exploratorium science museum in San Francisco. In 2009, the U.S. House of Representatives passed a resolution supporting Pi Day. In Japan, the Mathematics Certification Institute of Japan designated this date "Mathematics Day" in 1997. Pi Day is a celebration of the beauty and fun of mathematics, encouraging interest in science.

An Endlessly Fascinating Number

Pi is a number that has fascinated humanity for thousands of years.

• An irrational and transcendental number: Pi is an "irrational number" -- its decimal digits continue infinitely without repeating -- and a "transcendental number," meaning it can never be the solution to any polynomial equation with integer coefficients. German mathematician Ferdinand von Lindemann proved this in 1882, which also showed that the ancient puzzle of "squaring the circle" with a ruler and compass is impossible.
• A long history of calculation: Calculations of pi date back to ancient Babylon and Egypt. Today, computers have calculated it to more than 100 trillion digits. In Edo-period Japan, mathematicians such as Seki Takakazu and Takebe Katahiro also worked on calculating pi.

Interesting Facts About Pi

• Einstein's birthday: March 14th is also the birthday of physicist Albert Einstein -- and, remarkably, the date physicist Stephen Hawking passed away in 2018, a striking coincidence in the world of science.
• Memorization records: Some people compete to memorize as many digits of pi as possible -- one Japanese man holds an unofficial record for reciting 100,000 digits from memory.
• International Day of Mathematics: In 2019, the UNESCO General Conference proclaimed March 14th the "International Day of Mathematics," first celebrated in 2020.
• Pi time: Some people celebrate at 1:59 (or 15:09) on March 14, since 3/14 1:59 matches the first six digits of pi, 3.14159.
• Pi in literature: "Pilish" is a style of writing in which the number of letters in each word follows the digits of pi (3, 1, 4, 1, 5...) -- and entire novels have been written in this constrained style.

Endless Curiosity Opens New Horizons

Pi Day is a chance to reflect on the deep world of mathematics hidden within something as simple as a circle. Just as pi's digits never end no matter how far you calculate, human imagination and potential have no limits either. Today, take a moment to notice the round objects around you and appreciate the beauty of perfect balance. Continuing to engage with questions that don't have a single answer is what makes life a deeper, more intellectually rich adventure.

Ideas for Celebrating Pi Day

• Share a round apple pie or pizza, and enjoy it together while appreciating the wonder of pi
• Search online to find out at what position in pi's digits your birthday or another meaningful number appears
• See how many digits of pi you can recite — Japanese speakers use wordplay mnemonics such as "mi hitotsu yo hitotsu" (3.14159…)
• Attend a math event at a science museum or university and discover the grand stories behind the equations

Perfect Harmony Guides You Toward a Fulfilling Future

March 14th is a day when your efforts come together smoothly, like a circle, creating wonderful harmony. Just as pi continues infinitely, may your curiosity never run dry, opening door after door to new knowledge. May today be filled with intellectual excitement and the kind of happiness that, like pi, simply can't be divided into neat numbers!