# What is the value of pi?

beckden | Certified Educator

pi is an irrational number, that is the ratio of a circles circumference and its diameter.  Irrational numbers cannot be written as p/q where p and q are integers.  This means the decimal expansion of pi goes on forever and never repeats.  3.14 or 22/7 are approximations as are all decimal representations of pi.  That is why the symbol is used to denote the exact value.

The first 20 decimals of pi are

3. 141592653 589793238 5

Generally a calculator will have a button labeled `pi` which is the greek letter for pi and will give you 8 decimal approximation to pi.

The symbol `pi` or the name pi was not used until the 17th century.

The Babylonians used 3 or 25/8 for pi 3800 years ago.  The Egyptians sometimes used 256/81.  Both are within 1% of the real value.  Archimedes in the 2nd century BCE computed pi and found it's value somewhere between 220/71 and 22/7.

embizze | Certified Educator

Pi is a transcendental number. It is irrational (cannot be expressed as a fraction -- a number of the form `p/q` where p,q are integers.) The fact that it is transcendental means that it cannot be expressed in finite form using only the operations +,-,x,/ and radicals. (It is not the solution to an algebraic equation, with the normal restrictive definition of an algebraic equation.) The decimal expansion for pi is nonrepeating and nonterminating.

`pi~~3.1415926`

`pi~~22/7`

hala718 | Certified Educator

The value of pi is 3.14 or 22/7.

==> pi= 22/7 = 3.14.

nithublr | Student

It is ﻿﻿﻿the ratio of a circle's circumfrence/its diameter. You approximately get the ratio to be 22/7 that is equal to =>3.14159

kjarman | Student

Pi is approximately equal to 3.14. It is used to show the ratio of a circle's circumference to it's diameter.