February 7th is* e* Day! While not as famous as Pi Day, *e* Day celebrates the mathematical constant *e*, which has a wide range of mathematical applications. Here's a bit of background on *e* and why it's worthy of celebration!

As the history of mathematics has unfolded, mathematicians have discovered a number that, in addition to being useful in number theory, occurs over and over in describing nature in mathematical terms.

This number is the mathematical constant *e*. It is an irrational number (a non–repeating decimal) and also a transcendental number (it is not the solution of any algebraic polynomial). The first 20 decimal places of the numerical value of *e* are:

### e = 2.71828182845904523536...

Historically, *e* is sometimes called Euler’s Number after the master Swiss mathematician Leonhard Euler. It is also sometimes called Napier’s Number, in honor of John Napier, the creator of logarithms.

*e* is one of the most important numbers in mathematics, along with 0 and 1, the additive and multiplicative identities; i, the imaginary unit; π; and ϕ, the number of the Golden Ratio.

Like π, i, and ϕ, *e* appears unexpectedly in many areas of mathematics.

*e*is used to compute Continuous Compound Interest.*e*is used to compute various aspects of Atmospheric Pressure and many other natural phenomena.- The equations that describe Exponential Growth and Decay involve
*e*.

There are many ways to calculate the value of *e*. Let's take a look at one way of finding *e**:*

Check out this fun song tribute to *e* from Daniel Wedge!

While *e* Day might not have the cool factor π Day has, *e* is definitely worth celebrating. Make sure to wish someone a Happy *e* Day today!