**Pi**, written as **π**, is a universally recognized mathematical constant that is irrational, for it neither repeats nor terminates.

Below is what a ninth-grade geometry student memorizes of pi.

- $ \pi\, = 3.141592653589793238462643383279502884197... $

Below is the first 100 digits of pi.

- $ \pi\, = 3.1415926535897932384626433832795028841971693993751058209749445923078164062862089986280348253421170679... $

Mathematicians all over the world are continuing to find out the mystery of pi to this day. Though recent computations churn out 1 trillion decimals of pi, scientists only need a few hundred. Nevertheless, the record for the most digits of pi memorized, as of 2012, are 65,000.

## Attempts To Find PiEdit

Scientists have been trying to form an equation that precisely equals pi for centuries, even though pi is a transcendental number; it cannot be equated with a formula.

Below are a number of ways mathematicians dating back to the 1700s have attempted to reach pi with a formula.

- $ \frac{22}{7}\, > \pi\, $

- $ \int_{-1}^1\,\sqrt{1-x^2}\,dx = \frac{\pi\,}{2}\, $

- $ \frac{2}{\pi\,}\, = \frac{\sqrt{2}\,}{2}\, * \frac{\sqrt{2+{\sqrt{2}\,}}\,}{2}\, * \frac{\sqrt{2+{\sqrt{2+{\sqrt{2}\,}}\,}}\,}{2}\,... $

- $ \pi\, \approx\, \frac{2nl}{xt}\, $

- $ \pi\, = \frac{C}{d}\, $

## Pi DayEdit

Pi Day is an international holiday celebrated every March 14, in correspondence to the first three digits of pi.

## Other Uses of πEdit

A capital π is used in product notation as a large operator.

E.g.

- $ \prod_{x=1}^{10}x = 10! = 1 * 2 * 3 * 4 * 5 * 6 * 7 * 8 * 9 * 10 = 3628800 $