Every year as February turns to March, we circle one day on our calendar: March 14. Pi Day! While Congress officially recognized this is as "National Pi Day" in 2009, it's *always* been a holiday to us mathematicians.

(And just in case you don't have the first few digits of Pi memorized: 3.1415926535...)

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## **Full details**

Code: **PIDAY** at online checkout

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Duration: March 8-14

Area of a circle: 2πr^{2}