# Everything you need to know about 'Pi Day'

Tuesday a great day to be a math nerd. Tuesday is Pi Day.

In honor of the trillion-digit (no, seriously) ratio of a circle's circumference to its diameter, here's everything you need to know to get ready for Pi Day.

What is Pi Day?

It's celebrated on March 14, in honor of the number itself, which rounds up to about 3.14159.

I'm bad at math. What is Pi?

Pi is the ratio of the circumference of a circle to its diameter. It's rounded up because the actual ratio has been calculated to over one trillion digits beyond the decimal point (which sounds like fun to read while swiping on a phone). The symbol for Pi (π) was first used in 1737 by Swiss mathematician Leonhard Euler.

What can I do to celebrate?

NASA wants you to celebrate like a rocket scientist and issued a Pi in the Sky Challenge. It presents a series of math problems NASA engineers and scientists might solve by using Pi, such as how much of Earth would be covered by an eclipse, or how many days the Cassini spacecraft will need to orbit around Saturn.

You can also pay tribute by hosting your own "Pie Day." Here are a few recipes to get you started.

Wow, pie sounds awesome right now

Of course it does! But it also applies to pizza pies. Several pizza shops (and other restaurants) nationwide are offering deals, including pizzas for \$3.14. If you plan on buying a pie instead of baking, Whole Foods is offering \$3.14 off all large pies.

Meanwhile, if you have kids and live in the Northeast — where you are likely snowbound — the Pinterest search for "Pi Day activities" is your best friend.

USA TODAY

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