# Day 14 | LThMath Advent Calendar

In today's post I wanted to share a little creative way of showing some digits of * e*. The number

*, also known as*

**e****Euler's number**, is a mathematical constant approximately equal to 2.71828, and can be characterized in many ways. When used as the base for a logarithm, we call that logarithm the natural logarithm and write it as lnx. This is another interesting mathematical constants.

__General Information__

The (natural) exponential function *f*(*x*) = *e^x* is the unique function *f* that equals its own derivative and satisfies the equation *f*(0) = 1; hence one can also define *e* as *f*(1). The natural logarithm, or logarithm to base *e*, is the inverse function to the natural exponential function. The natural logarithm of a number *k* > 1 can be defined directly as the area under the curve *y* = 1/*x* between *x* = 1 and *x* = *k*, in which case *e* is the value of *k* for which this area equals one.

*e* is sometimes called **Euler's number**, after the Swiss mathematician Leonhard Euler (not to be confused with *γ*, the Euler–Mascheroni constant, sometimes called simply *Euler's constant*), or **Napier's constant**. However, Euler's choice of the symbol *e* is said to have been retained in his honor. The constant was discovered by the Swiss mathematician Jacob Bernoulli while studying compound interest.

A little bit of self promotion in here, I have used this design to create a little design that you can add to different items, such as T-shirts, hoddies, mugs, tote bags and a little sticker. If you enjoy the design, take a look at our __Teespring shop__.