Over the course of the year, there are certain days that celebrate people and ideas in science, science fiction, and mathematics. For instance, Star Wars has May The Fourth Be With You (May 4), followed immediately by Revenge of the Fifth (May 5). Trekkies have Captain Picard Day (January 23).
Mathematics also has its day. Today is National Pi Day.
A brief history
First described thousands of years ago by the Babylonians, Pi is now symbolized by π. The Babylonians calculated π to be 3.12.
Over the years, other calculations were made with more and more accuracy. Eventually Archimedes came along and described pi as the number we all know and love: 3.14. In the process, Archimedes came up with the famous equation for a circle, A= πr². This means the area of a circle is pi times the radius squared. He proved that this is a constant.
Isaac Newton calculated the number to 16 decimal places. Over time, other work increased the number of decimals until, in the modern era, computers figured over 31 trillion decimal places. If you would like to memorize the first 100 decimals, check out this song.
What’s in a name?
The name pi and symbol came from the 16th letter of the Greek alphabet. William Jones, a British mathematician, chose the name for the number in 1706. Pi itself originates from the Phoenician letter pe, meaning mouth.
That’s not rational
Pi is an irrational number, meaning it’s decimal places are infinite and non-repeating. It also means that it cannot be described by the ratio of two integers. For example, pi is represented as 22/7 in fraction form. Another irrational number is the Golden Ratio, or 1.61.
So, as you go through the day today, think about all the circles in your life. And how much 3.15 is important to us. Maybe even have some pie.
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