Pi Day – 14th March

Pi is a very old number. The earliest values of pi including the ‘biblical’ value of 3, were most certainly found by measurement. We know that the Egyptians and the Babylonians knew about the existence of the constant ratio pi, although they didn’t know its value nearly as well as we do today. They had figured out that it was a little bigger than 3. The Egyptians calculated it to be approximately (4/3)^4 with equals 3.1604 and the Babylonians had an approximation of 3 1/8 which is about 3.125.

The earliest known reference to pi occurs in a Middle Kingdom papyrus scroll, written around 1650 BC by a scribe named Ahmes. He began the scroll with the words “The entrance into the knowledge of all existing things” and remarked in passing that he composed the scroll “in likeness to writings made of old.” Toward the end of the scroll, which is composed of various mathematical problems and their solutions, the area of a circle is found using a rough sort of pi.

Around 200 BC, Archimedes of Syracuse found that pi is somewhere about 3.14. He wrote a book called “The Measurement of a Circle.” In the book he states that Pi is a number between 3 10/71 and 3 1/7. He found this out by taking a polygon with 96 sides and inscribing a circle inside the polygon. That was Archimedes’ concept of pi.

In the 1800’s people sat down for years on end to find the values of pi to about 100 places. Imagine doing this by hand with no calculators. This has become a thing of the past, since the tedium that used to be done by hand is now done by computer.

This is of course just a brief history of how people studied pi …