How are first digits of $\pi$ found? Since Pi or $\pi$ is an irrational number, its digits do not repeat. And there is no way to actually find out the digits of $\pi$ ($\frac{22}{7}$ is just a rough estimate but it's not accurate). I am talking about accurate digits by either multiplication or division or any other operation on numbers.
Then how are the first digits of $\pi$ found -

3.1415926535897932384626433832795028841971693993...

In fact, more than 100,000 digits of $\pi$ are found (sources - 100,000 digits of $\pi$)
How is that possible? If these digits of $\pi$ are found, then it must be possible to compute $\pi$ with some operations. (I am aware of breaking of circle into infinite pieces method but that doesn't give accurate results.)
How are these digits of $\pi$ found accurately? Can it be possible for a square root of some number to be equal to $\pi$?

In the 18th century, Leonard Euler discovered an elegant formula:
$$\frac{π^4}{90}=\frac{1}{1^4}+\frac{1}{2^4}+\frac{1}{3^4}+\frac{1}{4^4}+\frac{1}{5^4}+\frac{1}{6^4}+\dots$$
The more terms you add, the more accurate the calculation of $π$ gets.
$$\frac{π^4}{90}=\frac{1}{1^4}=1.000$$
then $π=3.080$
$$\frac{π^4}{90}=\frac{1}{1^4}+\frac{1}{2^4}=1.0625$$
then $π=3.080$
$$\frac{π^4}{90}=\frac{1}{1^4}+\frac{1}{2^4}+\frac{1}{3^4}=1.0748$$
then $π=3.136$
$$\frac{π^4}{90}=\frac{1}{1^4}+\frac{1}{2^4}+\frac{1}{3^4}+\frac{1}{4^4}=1.0788$$
then $π=3.139$
$$\frac{π^4}{90}=\frac{1}{1^4}+\frac{1}{2^4}+\frac{1}{3^4}+\frac{1}{4^4}+\frac{1}{5^4}=1.0804$$
then $π=3.140$
etc
This is a slow way to calculate them, since after the 100th term, $π$ is $3.141592$, but it calculates them nontheless.
