Question

What is `pi` (pi) ?

Answer 1

The ratio between the circumference of a circle and its diameter.

Explanation:

All circles are similar, so the ratio between circumference and diameter is the same for any circle.

We call that ratio pi, written using the Greek letter `pi`

`pi` is an irrational number a little larger than `3`.

Two good rational approximations for it are `22/7` and `355/113`.

In decimal it begins:

`3.141592653589793238462643383279502884196...`