The 'Math Guy' Presents 5 Facts About 3.14 Want to impress the guests at your local Pi Day celebration this Saturday (3/14/15, hopefully at 9:26)? Pick up some tidbits of mathematical trivia from Keith Devlin.

#### The 'Math Guy' Presents 5 Facts About 3.14

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The 'Math Guy' Presents 5 Facts About 3.14

# < The 'Math Guy' Presents 5 Facts About 3.14

#### The 'Math Guy' Presents 5 Facts About 3.14

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SCOTT SIMON, HOST:

Today is March 14, a day of the year when mathematicians around the world celebrate Pi Day. That mathematical constant denoted by the Greek letter pi, the number you get when you divide the circumference of a circle by its diameter. Back in 1988 on March 14, a physicist called Larry Shaw organized the first Pi Day celebration. It was at the Exploratorium in San Francisco, and youngsters marched around one of their circular rooms there and wound up eating fruit pies. Ever since, March 14 has been Pi Day. Celebratory events are organized across the United States and other parts of the world. But why March 14? Our own math guy Keith Devlin of Stanford University joins us. Keith, thanks so much for being with us.

KEITH DEVLIN: Thanks for having me on, Scott, and happy Pi Day to you.

SIMON: Happy Pi Day to you. Why March 14?

DEVLIN: OK, so it goes from the - when you take pi and you try to write it down as a decimal, the first thing to notice is you can't actually do that. If you start to enumerate the decimals of pi, it starts out 3.1415926 yada, yada, yada, and actually goes on forever without repeating or settling into some sort of nice pattern. So it's what mathematicians call an irrational number. But if you take the first two decimal places, you get 3.14. If you're American and you give dates in this crazy fashion that we do on this side of the Atlantic, as the month before the day, then you get 3/14 for 3.14. So that's March the 14. In fact, this year is a really, really special Pi Day...

SIMON: Yeah.

DEVLIN: ...Because it's 2015. So you actually have 3/14/15, so today is a very unusual Pi Day in that it gives us the year as well.

SIMON: Oh, mercy. What is a - what does a guy like you, a distinguished, erudite mathematician do on Pi Day?

DEVLIN: (Laughter) Well, what I do is I talk to my friend Scott Simon about Pi Day...

SIMON: Oh, right.

DEVLIN: ...And pi (laughter).

SIMON: Other than our conversation, what...

DEVLIN: The reality is, I share this sort of - the sensible reason why Larry Shaw did this. It's getting kids to sort of look at mathematics and think about mathematics. And as soon as you start talking about pi, that actually connects to almost all of mathematics and all of science and engineering because pi...

SIMON: Or radio, radio.

DEVLIN: Yeah, we couldn't be speaking on the radio if it wasn't for pi. We wouldn't be able to speak on a mobile phone or smartphone if it wasn't for pi. We wouldn't have computers. Celebrating Pi Day is a really good way to get kids aware of the role mathematics plays in today's world.

SIMON: Keith, here's a question that I haven't had a chance to ask you through the movie awards season, yeah. Who do you want to play you, Benedict Cumberbatch or Eddie Redmayne?

DEVLIN: Oh, that's an interesting one. They were both awesome...

SIMON: Now that mathematicians are so, you know...

DEVLIN: Oh, wow. I'll go for Benedict Cumberbatch.

SIMON: Oh, all right. Let me just - let me just check in the control room...

DEVLIN: (Laughter) Let's contact his agent.

SIMON: There's a feeling in the control room that that's begging credulity, but..,

DEVLIN: OK, I'll go for the other for the other guy then. I thought both performances were superb.

SIMON: Well, and because mathematicians are the most interesting people, aren't they?

DEVLIN: Well, I think so.

SIMON: Keith Devlin, executive director of the H-STAR Institute at Stanford University, our math guy and a fascinating man. Thanks so much for being with us.

DEVLIN: My pleasure, Scott. And once again, happy Pi Day to you and all our listeners.

(SOUNDBITE OF SONG, "LEIBNIZ'S SERIES FOR PI")

ZAMBRA: (Singing) 3.14159265358...

SIMON: And you can read more about Pi Day if you haven't had your fill of it with our own Keith Devlin. He's featured in The New York Times' Wordplay blog. We have a link to it on our Facebook page and these wonderful voices. This is Zambra. They're a choral group based in Santa Cruz, Calif.

(SOUNDBITE OF SONG, "LEIBNIZ'S SERIES FOR PI")

ZAMBRA: (Singing) ...7950 - 3.14159 - 197 - 3.1415...

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