Pi Day

Pi Day History

Pi Day celebrates the mathematical constant π (pi), 3.141592653... Pi is the ratio of a circle's circumference to its diameter. The circumference of a circle is defined as its arc length while the diameter is defined as the longest chord of the circle. Pi is a special number due to its infinite and pattern-less nature. This means that the digits after the decimal point never repeat themselves in a specific pattern.

Pi Day was established in 1988 by Physicist Larry Shaw. Shaw was an employee at the San Francisco Exploratorium where the first Pi Day was held. It took place on March 14th (3/14), given that the first digits of Pi are 3.14. On March 12, 2009, the U.S House of Representatives recognized March 14 as National Pi Day.

Top 10 Facts for Pi Day in 2026

• The annual observance of Pi Day serves as a dual tribute to the history of science, as it marks the birthday of theoretical physicist Albert Einstein and the anniversary of the passing of Stephen Hawking.
• The celebration was first established in 1988 by physicist Larry Shaw at the Exploratorium in San Francisco, where participants traditionally march in circles and consume various types of fruit pies.
• In a formal recognition of its global educational value, UNESCO designated the date as the International Day of Mathematics during its 40th General Conference in 2019.
• Enthusiasts of recreational linguistics have developed a constrained writing style known as Pi-lish, where the number of letters in each word must match the consecutive digits of the mathematical constant.
• The record for the most digits of pi memorized and recited stands at over 70,000, a feat achieved by memory athletes such as Suresh Kumar Sharma and Rajveer Meena.
• Literature for younger audiences often explores these geometric concepts through works like the children's book Sir Cumference and the Dragon of Pi by Cindy Neuschwander.
• High-level computation of the constant is frequently used by hardware engineers as a digital cardiogram to stress-test the processing power and stability of new supercomputers.
• The number's cultural reach extends into the luxury industry with the creation of the men's cologne Pi by Givenchy, which is marketed toward "visionary" and intellectual consumers.
• Mathematicians often point to a specific sequence of six consecutive nines starting at the 762nd decimal place, a phenomenon commonly referred to as the Feynman Point.
• NASA scientists rely on approximately 15 decimal places of pi for high-precision calculations required for Interplanetary Navigation and the deployment of space probes.

In the News and Trending in the US for Pi Day

Top things to do in the US for Pi Day

• Memorize as many digits of Pi as you can (remember, the World Record Holder was able to memorize 70,000 decimal places of pi).
• Eat a pie to celebrate Pi day and earn bonus points if your can calculate Pi for your pie's circumference! Here are some twists on traditional pies that you can try:
  1) Avocado and cream cheese pie
  2) Cheeseburger and pickle pie made from ground beef, cheese, and chopped dill pickles
  3) Mac and Cheese Pie topped with bacon
  4) Hot dog pie covered with a layer of cheese
  5) Twinkie pie topped with whipped cream
• Practice your geometry and algebra equations that contain the constant Pi. Here are some useful formulas to help you:
  Circumference of a circle = 2 πr
  Area of a Circle = π r^2
  Volume of a Cylinder = π r^2h
  where r=radius and h=height
• Go for a 3.14km walk to celebrate Pi Day.
• Watch movies about mathematics:
  1) Good Will Hunting (1997)
  2) A Beautiful Mind (2001)
  3) The Number 23 (2007)
  4) Rain Man (1988)
  5) The Theory of Everything (2014)