Pi is a mathematical constant representing the ratio of a circle’s circumference to its diameter. It is represented by the symbol π and is most commonly rounded to the number 3.14. However, because it is an irrational number, it cannot be written as a ratio of two integers. This essentially means it never ends and never repeats when expressed in decimal form. For instance, the longer form of the number is actually 3.14159 and so on. It cannot be produced with a finite sequence of algebraic operations, such as roots, powers, or sums. The numbers in pi’s decimal representation appear to be random, but so far, there is no way to prove that these numbers actually are random.

Pi is usually used in geometry and trigonometry in equations involving ellipses, sphere, or circles. It is also used in other areas of science including number theory, cosmology, fractals, statistics, mechanics, and electromagnetism. In ancient Babylonia, pi was calculated as the area of a circle by taking three times the square of its radius, giving it a value of pi = 3. One Babylonian tablet from somewhere between 1900–1680 BC indicates a value of 3.125 for pi, which is the closer approximation. There is also proof that ancient Egyptians calculated the value of pi to 3.16.

**Famous Names Related to Pi**

Mathematicians have been trying to understand pi for thousands of years. There have been scholars who have computed it to a high degree of

accuracy including some of the best known figures in science, such as Archimedes, Isaac Newton, and Leonhard Euler. Archimedes was among the first to officially prove a calculation for pi using geometry. He approximated the area of a circle by using the Pythagorean Theorem. This allowed him to find the areas of two polygons, one of which was circumscribed within another. What Archimedes actually did was prove that that the value of pi is somewhere between 3 1/7 and 3 10/71. Euler is often credited with associating the symbolic representation of pi with the number, which he began doing in 1737 based on the use of the Greek letter of a similar appearance.

**Modern Pi**

During the 20th century, new algorithms were discovered that produced a steady stream of records extending the decimal representation of pie to over a trillion digits. In general, scientific applications need no more then a few hundred digits when using pi, so the effort to extend it further was merely out of scientific curiosity or competition. However, the calculations used to extend pi have also been used to test supercomputers and multiplication algorithms that require very high precision.

In recent years, pi has been celebrated in main stream ways, such as the recognition of pi day on March 14 and the memorization of the number to more than 65,000 digits.