#### More about Tau:

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#
Pi Day

## For the Curmudgeons: Vi Hart’s Anti-Pi Rant

#### More about Tau:

## Happy Birthday, General Relativity

#### You may also enjoy:

## Pi: Who Needs That Many Digits?

#### How you round it off makes a difference:

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## Pi and Buffon’s Matches

#### For a kid-friendly version of this experiment, try throwing food:

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## Unending Digits… Why Not Keep It Simple?

#### Math Poetry Activity

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## Pi Day: It’s an Irrational Holiday

## Pi Makes a River Bend

### Update

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## Calculating Pi with Real Pies

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## A Bit About Pi

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## Playful Math Snacks: Why Pi?

### A Preview

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Don’t forget that Pi Day is also Albert Einstein’s birthday! And this year marks the 100th anniversary of his Theory of General Relativity. So Science Magazine has a special Einstein issue online, featuring this interactive comic:

- the Happy Birthday, Einstein! video series
- Happy Birthday, Einstein (Part 2)
- Happy Birthday, Einstein (Part 3)
- Happy Birthday, Einstein (Part 4)
- Albert Einstein’s math biography
- Math-related quotes from Albert Einstein

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From Numberphile: Pi is famously calculated to trillions of digits – but Dr. James Grime says 39 is enough.

An extra note from Dr. Grime: “Since pi39 ends in 0, you may think we could use pi38 instead, which has even fewer digits. Unfortunately, the rounding errors of pi38 are ten times larger than the rounding errors of pi39 — more than a hydrogen atom. So that extra decimal place makes a difference, even if it’s 0.”

From Numberphile: Dr Tony Padilla’s unique (and low budget) twist on the Buffon’s Needle experiment to learn the true value of Pi.

Do you have a favorite family activity for celebrating Pi Day? I’d love to hear it!

Unending digits …

Why not keep it simple, like

Twenty-two sevenths?—Luke Anderson

Encourage your students to make their own Pi Day haiku with these tips from *Mr. L’s Math*:

And remember, Pi Day is also Albert Einstein’s birthday! Check out this series of short videos about his life and work: Happy Birthday, Einstein.

CREDITS: Today’s quote is from Luke Anderson, via TeachPi.org. Background photo courtesy of Robert Couse-Baker (CC BY 2.0) via Flickr.

I just discovered this fun Pi Day song from The Singing Nerd. Definitely need to add him to my YouTube subscriptions.

Hat tip: Singing Banana.

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From Numberphile: “Sinuosity is a measure of how ‘bendy’ a river is. It is the length of the river divided by the direct route. Featuring Dr. James Grime.”

After posting this video, Dr. Grimes and Lawrence Roberts began collecting and analyzing data about real-world rivers. It turns out the pi theory of sinuosity is too simple. Read about their results:

From Numberphile: “How accurately can we calculate Pi using hundreds of REAL pies? This video features Matt Parker, who believes this is the world’s most accurate pie-based Pi calculation.”

Pi Day is coming soon. Maybe you’d like to try a pi project with your family? Check out my Pi Day Roundup of links.

From Numberphile: “Some stuff about Pi, the ‘celebrity number’. This video features maths-loving author Alex Bellos and Professor Roger Bowley from the University of Nottingham.”

Did you notice the error? It was supposed to be “a”…

Teachers and other math nerds are preparing to celebrate an epic Pi Day on 3/14/15. Unfortunately, the activities I see on teacher blogs and Pinterest don’t include much actual math. They stress the pi/pie wordplay or memorizing the digits.

With a bit of digging, however, I found a couple of projects that let you sink your metaphorical teeth into real mathematical meat. So I put those in the March “Let’s Play Math” newsletter, which went out this morning to everyone who signed up for Tabletop Academy Press math updates.

If you’re not on the mailing list, you can still join in the fun:

Math Snack: Why Pi?In math, symmetry is beautiful, and the most completely symmetric object in the (Euclidean) mathematical plane is the circle. No matter how you turn it, expand it, or shrink it, the circle remains essentially the same. Every circle you can imagine is the exact image of every other circle there is.

This is not true of other shapes. A rectangle may be short or tall. An ellipse may be fat or slim. A triangle may be squat, or stand up right, or lean off at a drunken angle. But circles are all the same, except for magnification. A circle three inches across is a perfect, point-for-point copy of a circle three miles across, or three millimeters…