
Neil deGrasse Tyson @neiltyson
Not Pi-fluent? Divide the Perimeter of any (flat) circle **of any size** by its own Diameter, you get the same number every time, represented by its very own Greek letter: Pi Useful in math, science, & engineering. Even appears in Einstein’s Relativity. And in Geeky kitchens. https://t.co/Wr49JnwsPZ — PolitiTweet.org