# E-number

The limit of the expression $(1+1/n)^n$ as $n$ tends to infinity:

$$e=\lim_{n\to\infty}\left(1+\frac1n\right)^n=2.718281828459045\dots;$$

it is the base for the natural logarithm. $e$ is a transcendental number, which was proved by C. Hermite in 1873 for the first time.

$e$ is also defined as the sum of the series

$$\sum _{n=0} ^{\infty} \frac{1}{n!}$$

That means

$$e=\sum _{n=0} ^{\infty} \frac{1}{n!}=\frac{1}{0!}+\frac{1}{1!}+\frac{1}{2!}+\frac{1}{3!}+\frac{1}{4!}+\dots$$