Do you know the so-called 'mathematical holidays'?

Everyone knows math, but not everyone gets along with it, and a significant portion of the population only know the name of the subject they studied (or at least should have) at school. However, whether people like it or not, it has many curious and, why not say, interesting facts.

One of the things few know is that there are so-called "mathematical holidays". Calm down, they are not extra dates off your calendar, but days adopted by mathematicians and scientists to represent, and in some cases even “celebrate”, some specific calculations and numbers. Here in Brazil, little is known about these dates, but these celebrations have a considerable tradition in the United States, as they originated there.

What is most striking about the days of these celebrations is that they are not chosen by chance and have to do with the theme they celebrate. Thinking about the importance of getting people to know more about these numbers, their dates, and their history, Mother Nature Network listed the top five "mathematical days" that everyone should know. So, to learn a little more about these points and remember some of the cool stuff you have already studied, check out the following list:

1. Mol Day

Mol Day is the date that celebrates the Avogadro constant, represented by the equation 6.02 x 10 ²³ . This number is a basic unit of measure in chemistry and was designed by physicist Amedeo Avogadro to calculate a "mol" of any substance.

The mol is a mass whose measurement in grams is equal to the molar mass of the molecule. Using the example of water, which has 18 molar mass, we have that its mol weighs 18 grams. In general, one mole of any substance contains the Avogadro constant times the number of molecules or atoms of that substance.

Understood? Well, if you didn't already know what this was all about, you probably didn't get it, but the important thing here is to know that the date on which Mol Day is celebrated is October 23, between 6:02 am and 6:02 pm. Yes, there is a specific time because it is the numbers that represent the Avogadro constant equation. In the American way of reading, the date would be 6:02 am 10/23 (remembering that there, the times are marked by “6:02 am” and “6:02 pm”).

The fact is that there is a foundation dedicated to Mol Day in the United States, whose purpose is to disseminate the date in schools and encourage the conduct of chemistry activities. It was created by a retired chemistry professor named Maurice Oehler in 1991 and has since been celebrated uninterruptedly. Each year, Mol Day has a different theme and in 2015, for example, the slogan was: “May the moles be with you”.

2. Fibonacci Day

Leonardo Fibonacci, an Italian from Pisa, developed a mathematical concept in which each sequence number is the sum of the previous two. To clarify, starting with 0 and 1, the first ten numbers are 0, 1, 1, 2, 3, 5, 8, 13, 21, 34 (0 + 1 = 1; 1 + 1 = 2; 2 + 1 = 3 and so on). This is called the “Fibonacci sequence”.

Thus, Fibonacci Day is celebrated on November 23, remembering that in the American format is written 11/23, as the first four numbers of the sequence. The date is symbolic, just to honor the relatively simple Italian mathematician responsible for the concept, but it is important in that it is present in various items of nature, including plants, hurricanes, shells and others.

The video below, made available on the Vimeo website, was produced by Cristóbal Vila and will help you better understand not only the concept of the Fibonacci sequence, but also how it appears in various components of our daily lives and nature.

NATURE BY NUMBERS from Cristóbal Vila on Vimeo.

3. Square Root Day

The square root does not have a specific annual commemoration date, but has days determined by years that represent exact roots. The concept was created by American professor Ron Gordon of Redwood City, California, when he announced the date of September 9, 1981 (9/9/81) as Square Root Day.

Since then, all days with numbers equal to that of the month in question and multiplied to the end of the year are considered Square Root Day. Thus, the last days of this celebration occurred on 2/2/04 and 3/3/09. Already the next that will occur is in April next year, on 4/4/16.

Square Root Day has its own website and Facebook page so that interested people can meet and exchange ideas in advance of the dates.

4. Sequential Days and Times

At one hour, two minutes, and three seconds on April 5, 2006, the reading, in American format, would be 1:02:03 5/4/06. This is an example of a day with sequential time. Although not made official as a date to be celebrated, many people keep looking at the calendar to find times when this phenomenon occurs. In Brazil, if we were to look, as the date reads otherwise, naturally the day quoted as an example would be May 4 of the same year.

5. Pi Day

Pi is represented by the digits 3, 14, so its day is March 14, or 3/14 for Americans. For those who don't remember, this number is the ratio of the circumference to its diameter, and is one of the most famous items in mathematics. Like the prestige of the number itself, Pi Day is also the most widespread “mathematical date” around the world.

The choice of this day was made by a physicist who worked at the San Francisco Exploratory, USA, in 1988. In 2009, the date of March 14 became the National Day of Pi celebration.

Thus, there are many forms of celebration or homage to Pi Day. According to the Mother Nature Network, in 2015, for example, American radio stations played the song “Pi” by English singer Kate Bush and, at the Exploratory, several events were held, such as pie parties and processions.

What other numbers or equations deserve a day to celebrate? Comment, say what the date would be and why, in the Mega Curious Forum