Happy PiDay everybody. We thought we'd celebrate with facts about Pi and Raspberry Pi

Today, as you may or may not know, is Pi day (the 14 March, or 3/14 as its written in America).

Obviously, that's a big deal to us. Pi (π) is our favourite transcendental number. But it's also the name of our favourite computer.

So we thought we'd gather some great facts about Pi, and stats about Raspberry Pi. So much Pi you'll be stuffed to the gills. You can follow PiDay on Twitter (#PiDay) where it's currently trending.

Happy Pi Day: PiDay facts to stun your friends

• Pi is the most famous irrational number. That means it cannot be expressed as a fraction (not that it’s crazy). Irrational numbers do not terminate or repeat. They go on forever.
• Pi isn’t alone. Other famous irrational numbers include Euler’s number (2.71 etc.) and The Golden Ratio (1.61 etc.).
• Pi was first calculated by Archimedes of Syracuse (287-212 BC).
• A mathematics teacher called William Jones first used “π” as a symbol for Pi in 1706.
• But it was the Swiss mathematician Leonhard Euler who made π a famous symbol in 1737. It’s been used ever since.
• There are 360 degrees in a circle. If you print out Pi to 360 digits, it ends in 360. Spooky!
• Even spookier! 3.14 spells PI.E in a mirror.  Credit: Imgur
• At position 763 there are six nines in a row. These numbers are known as the Feynman point after physicist Richard Feynman. A challenge for memory experts is to remember Pi up to this point.
• The most decimal places of Pi memorised, according to The Guinness Book of Records,  is 70,000. It was achieved by Rajveer Meena (India) at the VIT University, Vellore, India, on 21 March 2015.
• The computer record for calculating Pi is to 22,459,157,718,361 decimal places. It was set by Peter Trueb using a Dell PowerEdge R930 with 4 Xeon 2.50GHz cores and 1.2TB DDR RAM. The program was running for 105 days.
• You can download the first trillion digits of Pi from Peter’s blog. You can get all 22.4 trillion digits if you ask him nicely and offer to pay for the cost of all the disks.
• Albert Einstein was born on Pi Day (3/14/1879). Happy Birthday, Einstein!

Understand Pi with the power of GIFs

GIFs are often silly, but they can be useful for explaining maths concepts. Especially ones that involve trigonometry. Here are three GIFs that help explain how Pi works:

http://giphy.com/gifs/l4FGFxNFWntk68huo

Credit: Wikimedia Pi Animations

The numbers are the length of the circumference, and an arrow is placed on the diameter. How many diameters is that when the wheel rolls? A little over 3.

http://giphy.com/gifs/math-pi-3ohzdQ8Y1Pc37UTzjO

A circle's radius is one-half of its diameter. An arc is that length along the circumference. Laying the arcs along the circumference explains the classic C = 2πr formula.

Here is how Pi relates to Sine and Cosine:

via GIPHY

For more detail (and a better explanation) take a look at this Nerdist article.

Raspberry Pi facts and figures

So, how about our favourite computer? Here are some awesome facts about Raspberry Pi to help you on PiDay.

• The Raspberry Pi is now the world’s third best-selling computer (after Apple Mac and Windows-based PCs).
• With sales now over 12.5 million, the Raspberry Pi has beaten the sales of the Commodore 64 (according to an examination of the serial numbers).
• The best selling Pi to date is the Raspberry Pi 3 clocking up over 4 million sold.
• 500,000 Pi Zero boards have been sold. All were made in Wales.
• But 100,000 Pi Zero W boards were sold in the first four days.
• 6 Million Pounds went into The Raspberry Pi Foundation this year.
• The Raspberry Pi was launched on a leap day (29th February 2012). So technically it’s only one-and-a-bit years old.

Here is what the sales of Raspberry Pi look as a Pie chart, created in LibreOffice Calc on a Raspberry Pi:

If you have any more Pi, Raspberry Pi or pie facts. Or just want to talk about pie. Let us know in the comments. Happy PiDay!

Image credit: Pi Pie Pans: The Geekiest Way to Bake a Pie, Kickstarter