Pi Day: Date, About Invention, History and Interesting Facts

Pi Day: Pi is the ratio of a circle’s circumference to its diameter. Annually, Pi Day is observed on March 14th. In the mid-18th century, pi was represented by the Greek letter π. Read more about Pi, its history, its invention, and some interesting facts about it.

Pi Day: Date

• 2025: 14 March, 2025 [Friday]
• 2026: 14 March, 2026 [Saturday]
• 2027: 14 March, 2027 [Sunday]

To celebrate the day, NASA’s Jet Propulsion Laboratory is serving up a series of science and engineering questions that are related to some of the agency’s Earth and space missions. The mathematical constant π is usually abbreviated to 3.14, and so Pi Day is celebrated on March 14. Therefore, to celebrate the occasion, the STEM engagement office at NASA’s Jet Propulsion Laboratory in Southern California has released a quartet of illustrated science and engineering questions based on the missions of NASA, including the upcoming Lunar Flashlight and SWOT (Surface Water and Ocean Topography) missions, along with InSight and TESS, which is the Transiting Exoplanet Survey Satellite.

Pi Day is celebrated every year on March 14th. This day not only commemorates a very special number but also celebrates the birthday of the great scientist and mathematician Albert Einstein. Let us study more about the symbol Pi and Pi Day through this article.

What is Pi?

In Maths Pi (π) is a constant number and is the ratio of a circle’s circumference to its diameter. That is for any size of the circle the value of Pi will be the same. Diameter is the distance of a circle from edge to edge and circumference of a circle is the distance around. Pi is a constant number that is approximately equal to 3.14 or 22/7 and is represented by the Greek letter π.

Do you know that Pi is an irrational number i.e. a real number that cannot be expressed by a simple fraction? According to mathematicians pi is also known as an infinite decimal which means that after the decimal point, the digits go on forever and ever.

History:

On 14 March 1988, the first official large-scale celebrations occurred at the San Francisco Exploratorium. This event was organised by Larry Shaw a physicist. Do you know that several participants marched around a circle at this celebration and consumed fruit pies? Years after years it gained popularity and finally, the U.S. House of Representatives passed HRES 224 on 12 March 2009, recognising 14 March as Pi Day.

To approximate circles, the mathematician Archimedes used polygons with many sides and determined that Pi was approximately 22/7. In 1706, the Greek symbol π was first used by William Jones. Do you know that a ‘p’ was chosen for the ‘perimeter’ of circles and so π became popular and was adopted by the Swiss mathematician Leonard Euler in 1737?

Celebrations:

On this day various celebrations occur worldwide with several activities like people reciting Pi and seeing who can get the furthest. In Museums and Science centres educational programs, music, pi memorisation challenges, and math fans celebrate this day by simply enjoying a slice of the pie. Numerical fun is also sometimes accompanied by delicious food items like pizza pie, fruit pie, etc. As we know that pi is used in formulas in math and physics.

Some interesting facts about Pi

• Pi is an irrational number; it is not possible to calculate Pi by dividing an integer by any other number.
• Pi is a never-ending and never-repeating number.
• As the value of Pi is never-ending, we can’t find the true circumference or area of a circle.
• In Greek alphabets, Pi is the sixteenth letter and in English, p is also the sixteenth letter.
• Pi is the ratio of a circle’s circumference to its diameter.
• In the 19th century, William Shanks calculated the first 707 digits of Pi by hand but unfortunately, he made a mistake after 527th place.
• A Japanese scientist, breaking all the previous records, with the help of the Hitachi SR 8000, which is a powerful computer, found 1.24 trillion digits of Pi.
• Pi is mentioned in the Bible.
• In ancient times, Archimedes was the first person to study Pi.
• Albert Einstein was born on Pi Day.
• There are no zeros in the first 31 digits of Pi.
• Various other names of Pi are Ludolph’s Number, Archimedes constant, Circular constant, etc.
• In 1706, William Jones introduced the symbol Pi, which was popularised by Leonhard Euler in 1737.

Since 2009, Pi Day has been a recognized national holiday. An annual celebration of the mathematical symbol pi takes place on March 14. March 14 was chosen as the founding date in 1988 by physicist Larry Shaw because it is Albert Einstein’s birthday and the numerical date (3.14) represents the first three digits of pi.