Happy 'e' - day

Hello friends ,
Today is 2nd of July , 2018 that is 2-7-18 (2.7.18).
We know 'e' as Euler's number/

The Value of 'e' :

'e' is an irrational number with value 

          e = 2.718...

The few digits are:

2.7182818284590452353602874713527....

It is often called Euler's number after Leonhard Euler (Pronounced "Oiler").

'e' is the base of the Natural Logarithms which was invented by "John Napier".

Calculating :

There are many ways of calculating the value of e , but none of them ever give a totally exact value, because e is irrational.

But it is known to over 1 trilllion digits of accuracy.

For example, the value of $(1 + \frac{1}{n})^n$ approaches e as n gets bigger and bigger.

i.e.$e = \displaystyle  \lim_{n\to\infty}(1+ \frac{1}{n})^n $

Another Calculation :

The value of e is equal to $\frac{1}{0!} +\frac{1}{1!} +\frac{1}{2!} +\frac{1}{3!} +\frac{1}{4!} +\frac{1}{5!} +\frac{1}{6!} +\frac{1}{7!} +... (etc) $

The first few terms add up to : $ 1+1+\frac{1}{2}+\frac{1}{6}+\frac{1}{24}+\frac{1}{120} = 2.718055556 $

Euler himself used this method to calculate e upto 18 digit places.

And the most beautiful equation in mathematics is 

$ e^{ i \pi} + 1 = 0 $

Thank you!