5 Math Holidays Everyone Should Know

Some people love math more than others — but math-related holidays are for everyone. Halfpoint/Shutterstock

If today were Mole Day, we'd give you a pass if you thought it was a celebration of the small burrowing rodent.

Mole Day is only one of the modern "holidays" that honors scientific concepts. In recent years mathematicians and scientists have begun campaigns to mark certain dates in celebration of significant principles and here are a few to add to your calendar:

1. Mole Day

Mole Day is celebrated annually on Oct. 23 from 6:02 a.m. to 6:02 p.m., according to the website of the National Mole Day Foundation. It commemorates Avogadro’s Number (6.02 x 10 23), which is a basic measuring unit in chemistry.

The first Mole Day took place in 1991 and has been honored every year since. Each Mole Day has a specific theme with such titles as The Mole the Merrier, Rock N' Mole and Mole-O-Ween. (The 2019 theme was DespicaMOLE Me!)

The foundation's mission is to foster interest in chemistry, encouraging schools around the globe to celebrate Mole Day with various activities related to chemistry and moles.

The concept of a celebratory day was created by Maurice Oehler, a retired high school chemistry teacher from Prairie du Chein, Wisconsin, and the foundation now claims about 3,000 members.

2. Fibonacci Day

You can see the spiral of this Comfrey flower's stalk. (Photo: Mikhail Melnikov/Shutterstock)

Nov. 23 marks Fibonacci Day, a special day that celebrates the man known as Fibonacci (aka, Leonardo of Pisa) who developed a mathematical concept called the Fibonacci Sequence, in which every number is the sum of the previous two numbers. So, for example, 11/23 marks the day because 1+1 equals 2, and then 1 + 2 equals 3 (the date being the 23rd).

It may be somewhat difficult to grasp, but the concept is not entirely theoretical. One of the main features of the Fibonacci Sequence is that it occurs so frequently in nature, including plants, shells, hurricanes and DNA molecules.

3. Square Root Day

Square Root Day is a holiday that heartily honors those dates where the combination of day and month and year form square roots: e.g. 2/2/04 and 3/3/09. The last Square Root Day was 4/4/16 and the next one will be 5/5/2025.

The holiday was created by a high school teacher Ron Gordon in Redwood City, California, who noticed that an upcoming date (9/9/81) represented a square root. Square Root Day has its own website and a Facebook page where celebrants can gather before the next holiday.

4. Sequential time days

Not officially a holiday, per se, but a good percentage of people know of the observance of "sequential time days" where the time and day and year form a numerical sequence — such as two minutes and three seconds after midnight on April 5, 2006 — which can be represented numerically as 1:02:03 4/5/06.

5. Pi Day

An apple pie with the pi symbol carved into the crust
An apple pie celebrates the arrival of Pi Day. koka_sexton [CC BY 2.0]/Flickr

The grandaddy of mathematical and scientific holidays, however, falls every year on March 14. The date, 3/14, represents the first three numerals in the calculation of pi, hence the date is known annually as Pi Day.

Pi Day was founded in 1988 by a physicist working at the Exploratorium in San Francisco. The observations spread to the point where, on March 12, 2009, the U.S. House of Representatives passed a resolution declaring March 14 as National Pi Day.

Celebrations are held around the world, but the Exploratorium continues to spearhead festivities. The 2015 event featured the eating of various pies, tossing pizza pie dough and processions and speeches. Radio stations such as NPR have been known to play the song "Pi" by English singer/songwriter Kate Bush in honor of the day.

The year 2015 also marked a monumental pi moment at 9:26:53 (a.m. or p.m.), as 3/14/15 9:26:53 represents the first 10 numerals in the calculation of pi.

These holidays, particularly Pi Day, are catching on with the general populace. Who knows? Maybe there's a National Fraction Day or International Algebra Week in our future.