The world of mathematics is, as far as we know, based on a number of equations, constants, and relationships between things, some of which we understand, and some of which we do not. One of the most well-known, and important, of these relationships is Pi, which refers to the fraction of approximately 22/7, or 3.14. The figure for Pi expresses the relationship between a circle's diameter and its circumference, with the circumference of a circle being exactly Pi times its diameter. Pi has been known to humans for several thousand years, and although its exact origins are unknown, it is believed that the Ancient Chinese and Ancient Greeks independently understood the relationship that we express as Pi, and had approximate values for it. Here, we will outline the history of Pi, first talking about its discovery in ancient times, before then looking at the advancements made during the enlightenment and into the 1800s, and finally looking at ways that we are advancing our understanding of Pi today.
The first written reference to Pi was found on tablets from Ancient Egypt and Babylon, where mathematicians had an approximate understanding of the relationship between a circle's diameter and its circumference-these civilizations approximated Pi as 25/8, or 3.12 (Arndt & Haenel, 2001). Pi was also independently understood by the Ancient Chinese and Ancient Greeks, with both civilizations understanding the approximate relationship by around the year 0 (Arndt & Haenel, 2001). These civilizations made improvements upon the understanding of Pi, with the Ancient Chinese in particular understanding Pi to at least 5 decimal places as early as 500 AD. This understanding was largely obtained using algorithms on very complex shapes, such as polygons, and these algorithms were able to further whittle down the approximate value of the relationship between a circle's diameter and circumference (Arndt & Haenel, 2001).