Today’s Farmdoc’s Blog post’s devoted to Pi Day [1, 2] which was last Monday. So I’m three days late. Better late than never, eh. Pi Day celebrates pi (ᴨ)  – the 16th letter of the Greek alphabet. It’s the mathematical constant formed by dividing a circle’s diameter into its circumference. Here are some facts about pi and Pi Day:
· Pi is so named because it’s the first letter of the Greek word for ‘perimeter’.
· Pi was first used with its current mathematical meaning in 1706.
· Pi Day is on 14 March, or as the Americans put it, 3/14. This is because pi begins 3.14.
· Pi’s decimal representation’s infinite. And no numerical sequence in it ever repeats.
· Pi has been computed to over a trillion digits.
· The ratio of the perimeter to the height of the Great Pyramid at Giza (constructed c. 2589-2566 BCE) is exactly twice pi.
· The Guinness-recognised record for reciting digits of pi is 67,890. It took a Chinese graduate student 24 hours and 4 minutes to do it – without an error.
· In 2015, Pi Day will reflect the first five digits of pi, i.e. 3/14/15.
· A common method of celebrating Pi Day is by eating its homophone, i.e. pie.
· Pi Day’s website’s a wealth of more good stuff about pi .
So, friends, I wish you, belatedly, Happy Pi Day.
P.S. It’s only 127 days to Pi Approximation Day - on 22 July (i.e. 22/7) because the fraction 22/7 is a common approximation of pi.