2).Introduction to pie(π)__.  :::

The number π is a mathematical constant. Originally defined as the ratio of a 

circle's circumference to its diameter, it now has various equivalent definitions

 and appears in many formulas in all areas of mathematics and physics. It is 

approximately equal to 3.14159 not a physical constant.

  π appears routinely in describing fundamental principles of the universe, often  

because π's relationship to the circle and to spherical coordinate systems. A 

 Simple formula from the field of classical mechanics gives the approximate 

period T of a simple pendulum of length L, swinging with a small amplitude (g is the earth's gravitational acceleration):

${\displaystyle T\approx 2\pi {\sqrt {\frac {L}{g}}}.}$

Below is the 100 digits of pie which goes to infinite:-

3.141592653589793238462643383279502884197169399375105820974944592307816406286 .....................

The entire universe exists in pie.
Pie day is celebrated on 14 march and this day is also know as mathematical constant day or maths constant day.
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