# 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:

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

Mar. 12, 2021

On March 14, the International Day of Mathematics will be celebrated worldwide under the theme “Mathematics for a Better World”.

Organized by the International Mathematics Union, the IDM includes a mixture of virtual and face-to-face celebrations in 2021, on all continents: from Madagascar to Gambia, from Panama to Chile, from Albania to Malaysia, from Bangladesh to Australia, people all over the world (in...Read more

Jun. 10, 2020

On June 10 2020 our latest exhibition I AM A. I. will launch in a digital format. Originally conceived as a travelling exhibition, due to the pandemic situation, we developed new formats to bring I AM A. I. into every household around the globe. Available on www.i-am.ai.Read more

Mar. 14, 2020

On 14 March 2020, the first-ever International Day of Mathematics will take place, celebrating the beauty and importance of mathematics in our everyday lives. This recurring event, proclaimed by UNESCO and co-organized with the International Mathematical Union...Read more

Nov. 26, 2019

To celebrate the beauty and importance of mathematics and its essential role in everyone’s life the International Mathematical Union (IMU) has led the project to have UNESCO proclaim March 14 as the International Day of Mathematics (IDM). Today, on November 26th 2019, the 40th General Conference of UNESCO approved the Proclamation of March 14 (Pi Day) as the International Day of Mathematics.Read more

Aug. 7, 2019

I. AM.AI is the name of IMAGINARY’s new exhibition project aiming to communicate Artificial Intelligence, how it works, and its social impacts, to the public.

The exhibition, supported by the...Read more