The Pi Approximation Day or Casual Pi Day is annually observed across the globe on 22 July to highlight the importance of the mathematical constant Pi (π), which is represented using the Greek letter π.
- Pi Approximation Day was first celebrated in 1995 at Chalmers University of Technology in Gothenburg, Sweden.
Why 22 July?
The date 22 July, written as 22/7 in day/month format, represents the fractional approximation 22 divided by 7, which equals approximately 3.142857, very close to the actual value of pi, 3.14159.
What is Pi (π):
i.Pi (π) is an irrational and transcendental number that denotes the ratio of a circle’s circumference to its diameter.
ii.Pi is usually approximated as 3.14, and since it is an infinite, non-repeating number, fractions like 22/7 are often used for convenience in calculations.
iii.It has been a fundamental element in mathematics, particularly in geometry, trigonometry, physics, astronomy, engineering, and computer science.
Historical Background of Pi(π):
i.Archimedes, the ancient Greek mathematician, was the first to estimate the value of Pi using a geometric method. He proposed 22/7 as a close rational approximation of Pi, which is why Pi is also known as Archimedes’ constant.
ii.The Greek letter “π” was first introduced as a symbol for Pi in 1706 by Welsh mathematician William Jones and popularised by Leonhard Euler in 1737.
iii.The symbol “π” was chosen because it is the first letter of the Greek word perimetros, meaning perimeter.
Related Observance:
i.Tau Day, also called Two-Pi Day, is celebrated on June 28 (6/28, Month/Day), symbolizing the mathematical constant τ (tau), which represents the ratio of a circle’s circumference to its radius.
- Tau is equal to 2π and is approximately 6.28, making it a significant constant in various mathematical formulas.
ii.Pi Day:
i.Pi Day is celebrated every year on March 14 (3/14, Month/Day) to honour the mathematical constant π (pi), which represents the ratio of a circle’s circumference to its diameter. The date (3/14) reflects the first three digits of pi: 3.14.
- The day also marks the birth anniversary of Albert Einstein (March 14, 1879).
- Renowned physicist Stephen Hawking passed away on Pi Day (March 14, 2018).
ii.Pi Day was created by Larry Shaw, the “Prince of Pi”, in 1988 at the San Francisco Exploratorium, California, the United States of America (USA), where he linked the mathematical constant pi (3.14…) with the date March 14 (3/14) during a staff retreat.
iii.Additionally, Pi (π) day is also celebrated on November 10, which is the 314th day of the year (or November 9 in leap years), reflecting the approximation 3.14 for Pi.
