# e-day - A mathematical holiday celebrated on February 7th

e-day - A mathematical holiday celebrated on February 7th
Feb. 7, 2018

Today, February 7th, 2018, is called e-day because e is approximately 2.718, and this date is written 2/7/18 in some parts of the world.

e, also called Euler’s Number after the Swiss mathematician Leonhard Euler, is a very important constant that comes up in many different places in mathematics. The numer e was discovered by the Swiss mathematician Jacob Bernoulli while studying compound interest where e arises as the limit of (1 + 1/n)n as n approaches infinity. e can also be calculated by summing:

The constant e appears naturally on the exponential function, which models growth. Hence, the same way that the constant π appears in everything that is round, the number e appears in everything that grows: size of baby animals, leaves in trees, bacteria populations, spreading of diseases, spirals in flowers and snails, radiactive decay of elements, money invested in a bank, processing power of computers… Everything that grows the faster the bigger it is follows an exponential law, and contains the number e.

e has an infinite number of digits. We prepared a website listing the first 60.000 digits of e and help you find your birthday in it:

e-day website

If we assign a number to each letter in the alphabet we can even find your name within the digits of e, along with the complete works of William Shakespeare, the ending of Game of Thrones (spoiler alert), the full text of the Wikipedia from the year 2030 or what you’ll have tomorrow for breakfast…

At least that’s what conjectured: It is conjectured that e is a normal number. In normal numbers every possible sequence of digits of a certain length appears with the same frequency. There are approximately as many 1s as 9s, as many 23s as 42s, as many 0000s as 1111s, etc. So within the infinite digits of a normal number we are able to find any possible sequence of any finite length.

Happy e-day to you!

## All News

May. 21, 2013

Today the sixth Russian IMAGINARY exhibition opens its doors in Tomsk, Western Siberia. It is coordinate and organized by the German Embassy in Moscow in collaboration with the Polytechnical University of Tomsk. It will be open for the public from the 21st of May until the 3rd of June 2013.

Apr. 30, 2013

In August 2013, the 3rd regional school of natural sciences “Laboratory Z” for gifted children (grades 6-8), will take place in famous Akademgorodok of Novosibirsk, Russia.

The goal of the summer school “Laboratory Z” is interest, immersion and expansion of students’ knowledge in subjects of mathematical, natural sciences (physics, chemistry) and technical (robot technology) areas. However, in the summer school there are no classes in...Read more

Apr. 17, 2013

There is still more than one week left to participate in the ongoing SURFER picture competition, so start being creative and upload your images! The competition, that started already on May 18, 2012 will run until April 28, 2013. Then a judging panel will decide about the winners of the competition.

Algebraic surfaces are produced by simple equations in three spatial coordinates x,y,z. All points which satisfy...Read more

Apr. 16, 2013

The Bridges conference 2013 about the connections between art and mathematics takes place from July, 27th until July, 31th, 2013, in Enschede, Netherlands. The most recent works at the interface of mathematics, music, art, architecture and culture will be presented.

Some highlights besides the conference program: art exhibition, experimental theater, Mime-Matics night, public lecture, music night, short film festival, poetry day,...Read more

Apr. 4, 2013

This Friday, April 5, a special IMAGINARY exhibition featuring sculptures and images will be shown for the first time in Denmark, at the Steno Science Museum in Aarhus, see here for the event info. It will be open until August 31, 2013. Then the exhibition series in Russia will find its continuation in a one week exhibition at...Read more