Stephen Johnson is Senior Staff Writer for Lifehacker where he covers pop culture, including two weekly columns “The Out of Touch Adults’ Guide to Kid Culture” and “What People are Getting Wrong this ...

Pi, a mathematical constant denoted by the Greek letter π, is the ratio of a circle's circumference C to its diameter d: π = C/d. The circumference of a circle is, in turn, equal to 2πr, where r is ...

March 14—aka Pi Day—isn’t just for math nerds. It’s the one day a year where we celebrate the magic of the number π (pi), which starts at 3.14 and goes on forever. But Pi Day isn’t just about ...

Happy Pi Day! The annual celebration, held every March 14, is your chance to pay tribute to the most famous constant in math and physics: the number you get when you divide the circumference of a ...

Test yourself on math's most famous constant with this pi quiz. When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. On March 14 mathematicians ...