# It's Pi Day in the USA

We know, it's not rational, but the world is envious of American exceptionalism today – the one country and the one day of the year where the month/day/year format adds fun to our lives and one can celebrate Pi Day. Every year we update this post with new Pi fillings.

TreeHugger Katherine is full of suggestions for keeping the kids busy if they are underfoot and bored. Here's a new one: memorize Pi. The kid who can remember the most digits gets first dibs on pie.

More fun with the kids: According to the San Francisco Exploratorium, you can estimate Pi with toothpicks.

Grab a box of toothpicks to recreate the method known as Buffon’s Needles, which allows you to calculate π just like 18th-century French naturalist (and gambler) Georges-Louis Leclerc, Comte de Buffon. Buffon was inspired by a then-popular game of chance that involved tossing a coin onto a tiled floor and betting on whether it would land entirely within one of the tiles. This method is absurdly inefficient—but you’ll also be surprised that you can calculate π this way.

Lloyd Alter/ seen in Toronto's St. Clair West Station/CC BY 2.0

Canadian medical experts are now recommending that citizens not visit the Great Petri Dish to the south, which is especially frustrating when Pi is illegal in Toronto, and Pi Day doesn't happen when you state the date logically.

Over on MNN, Melissa covered pi in great detail with 8 odd facts about pi.

Herein we round up some of our favorite older Pi Day posts:

So why is Pi Day green? We have justified it by noting that, "As Bucky Fuller would remind you, a circle encloses the maximum area per unit of perimeter, a sphere the maximum volume. It is theoretically the most efficient form," and we are all about efficiency. That's why we start with the Picycle, created by Tang Yau Hoong; it combines the efficiency (and round-ness) of the bike with Pi.

Here is a (dare I say?) roundup of round buildings – not from A to Z, but from Bucky to Yurts. More on TreeHugger.

Last year our roundup included this important Pi Chart, among other stories.

Two years ago we showed this trivet on which you can cool your pi.

Get on yer bike London/Promo image

Warren started it all in 2008 with his paean to his favorite thing that goes round, the bicycle.

In case you feel like baking, here is Kelly's recipe for Apple Pi.

via Core77/Screen capture

While we are discussing Apple Pi, you can join me as I Pi-le on Apple's new round headquarters.

It's Pi Day in the USA
It's not rational, but it's fun.