In the USA, 14th March is called PI day, because the date is written 3.14, and is a mathematical equation that represents the relationship of a circle’s circumference (the outside length) to the diameter. If you take a circle and measure it’s width as one unit, when you roll the circle it will measure 3.14… of that width.

## Pi

The earliest use of the Greek symbol for Pi is from the Welsh mathematician William Jones in 1706 but it is believed that it had been used in different forms since 2000BCE. Archimedes in around 280BCE created a formula to calculate it but it was only in 480CE that Pi was calculated to 7 decimal places.

Although Terry Pratchett joked that his mathematician “Bloody Stupid Johnson” had set Pi to 3 and that explained why all his inventions went wrong in spectacular ways in his Discworld novels. Ironically, this also the number recorded in the Bible as “…a molten sea, ten cubits from the one brim to the other: it was round all about,… a line of thirty cubits did compass it round about.”

## Pi Day

Pi Day is the international day of mathematics as set by UNESCO in November 2019.

It is an excuse for Americans to eat and throw pies, because they have a thing about pies.

## Raspberry Pi

The Raspberry Pi is not related to Pi Day, but came about because of the founder seeing a decline in the number and skill set of students applying to study at the University of Cambridge and remembered what started him on his journey was the BBC Model B that also came out of the University of Cambridge in the 1980s.

In 2012, the first Raspberry Pi was sold and by 2019, 30 million units had been sold.

In 2015, the Pi Zero was launched and this year the Pi Pico was launched in January.