Today is Pi (π) Day. Pi Day is an annual celebration of the mathematical constant π (pi). It is a celebration of mathematics, mystery, and perhaps, a slice of pie. Pi Day is celebrated on March 14th each year. The date is chosen to represent the first three significant digits of π, 3.14. This date also happens to be Albert Einstein’s birthday, adding an extra layer of significance for some math and science enthusiasts.
π is the ratio of a circle’s circumference to its diameter. It is a constant number, meaning that for all circles of any size, π will be the same. π is an irrational number, which means it cannot be expressed as a simple fraction and its decimal representation is infinite and non-repeating. It has puzzled and inspired minds since antiquity. From the clay tablets of Babylon to the papyrus scrolls of Egypt, the quest to understand this irrational number has been a saga spanning cultures and epochs.
Pi Day is often marked by various math-related activities. Enthusiasts often celebrate Pi Day by trying to recite as many digits of π as they can from memory. Some people eat pie, others throw pie-throwing contests, and many schools hold mathematics competitions or educational events exploring the importance of π in mathematics and engineering.
Similar events or days that celebrate mathematical concepts include:
e Day: Celebrated on February 7th, because the number e (Euler’s number, another important mathematical constant) is approximately 2.718. It’s less well-known than Pi Day.
Fibonacci Day: Celebrated on November 23rd, as the date 11/23 corresponds to the first numbers of the Fibonacci sequence. It’s a day to appreciate the beauty and application of the Fibonacci sequence.
Mole Day: Observed on October 23rd from 6:02 a.m. to 6:02 p.m., this day commemorates Avogadro’s Number (approximately 6.02×10^23), which is a basic measuring unit in chemistry.
Square Root Day: These are celebrated on dates where the day and the month are both the square root of the last two digits of the year, for example, 4/4/16. These are rare and only come nine times in a century.
Tau Day: Celebrated on June 28th (6.28), in recognition of the constant τ (tau), which is equal to 2π, or approximately 6.283185307179586. Some mathematicians argue that tau is a more natural and intuitive constant than pi because it represents the ratio of a circle’s circumference to its radius, not its diameter.