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

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

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!


Todas las noticias

10 Nov. 2015

Las instantáneas son artículos cortos y de fácil comprensión sobre temas recientes de investigación matemática. Describen problemas e ideas matemáticas de un modo accesible y comprensible, y arrojan luz sobre los temas de actualidad en la comunidad matemática a cualquiera que esté interesado en la matemática contemporánea.

Las instantáneas están escritas por verdaderos expertos en sus campos....Leer más

5 Jul. 2015

We are very happy to share the good news with you!

At the opening of the Mathematics of Planet Earth (MPE) exhibition in Heidelberg today, a new collaboration project was announced:

...Leer más
29 Jun. 2015

We have two big exhibition openings coming up in early July!

On July 5, the “Mathematics of Planet Earth” exhibition will open at Karlstorbahnhof in Heidelberg, Germany! It runs from July 5 to Aug 2, 2015, and offers a big variety of exciting adventures for children and adults alike. This exhibition is organized by the...Leer más

23 Abr. 2015

Thanks to the work of the NIMS-IMAGINARY team at CAMP, we now present the whole IMAGINARY platform in Korean, hoping to attract more of the Korean public interested in mathematics.Leer más

1 Abr. 2015

It is with great sadness that we announce that Klaus Tschira died unexpectedly on March 31, 2015, aged 74 years.
He was a friend and big supporter of IMAGINARY. His death is a great loss to all who knew him and for science that he so passionately promoted.Leer más