14th March has been officially designated Pi Day, a day for which we can celebrate the glorious number that starts with 3.14. Coincidentally, the 14th of March is also Albert Einstein’s birthday.

\(\pi\) -the ratio of the circumference of a circle to its diameter- has been calculated to over one trillion decimal places. The record as far as I know belongs to Alexander J. Yee & Shigeru Kondo, who have calculated \(\pi\) to 10 trillion digits [1]. As an irrational and transcendental number, \(\pi\) will continue infinitely without any repetition or patterns emerging.

The “pi man” Larry Shaw |
The first Pi Day was organized by Larry Shaw and held in San Francisco in 1988. In 2009, the US House of Representatives backed its official designation. |

**What to do for Pi Day?**

Suggestions include bake a pie for Pi Day, or be artistic and write a piece of music, a poem or make a painting. You can find lots more suggestions by following this link.

**The Welsh connection**

The earliest known use of the symbol \(\pi\) to represent the ratio of the circumference of a circle to its diameter is by Welsh mathematician William Jones FRS (1675 – 3 July 1749) in 1706 [2].

*Portrait of William Jones by William Hogarth, 1740 (National Portrait Gallery)*

Jones was a close friend of Sir Isaac Newton and Sir Edmund Halley. In November 1711 he became a Fellow of the Royal Society, and was later its Vice-President.

**References**

[1] Alexander J. Yee & Shigeru Kondo, Round 2… 10 Trillion Digits of Pi 2013.

[2] William Jones, *Synopsis Palmariorum Matheseos*, 1706.

**Links**

Pi Day