# Some squares sum squares to celebrate Pythagoras

If you enjoy Pi Day (3/14) and Avogadro's Number Day (10/23), then get this: today is a Pythagorean triple date.

You'd have to be a serious math nerd to recognize that the sum of the squares of 5 and 12 equals the square of 13. Which is exactly what the co-founders of the National Museum of Mathematics (MoMath) noticed.

So, along with some 2,000 fellow math geeks and museum staff, MoMath co-founder Cindy Lawrence will help surround the most well-known right-triangle-based edifice in the country -- New York's Flatiron Building -- and execute a glow-stick proof of the ancient Greek mathematican's famed theorem.

"You know about a 5-12-13 right triangle?" Lawrence asked, hopefully. "So, we decided we would celebrate today as Pythagoras Day, since it's one of the few days in the calendar that works out to be a Pythagorean triple. And then we knew the Flatiron Building was roughly a right triangle, and we thought: well, maybe we should do something with that."

The building is formed by angles of 23, 67 and 90 degrees, according to most sources. If you take "Rise of the New York Skyscraper" as an authority, its base is 87 feet by 173 feet by 190 feet -- not precisely a Pythagorean triple, but close enough. (Adding some elbow room to make it 90 x 216 x 234 works out, though.)

"We thought: this is too good to pass up, so we're going to go out there and measure the Flatiron Building, and we're going to do it with the units of measure being glowing sticks," Lawrence said.

So, how many people would that take? They figured maybe 450. That seemed a bit optimistic, but they put out an email.

"We said: Let's see what happens. Maybe we'll have one person holding two sticks, then we'd only need maybe 225 people, maybe that could work. So we just put out one email, and on the basis of that one email, we have more than 2,000 people signed up to show up."

Organizers were elated, but now had a new mathematical problem: how to fit 2,000 people into a 19,000-square-foot headquarters, a few blocks north, and serve each about 8 ounces of hot chocolate. The answer: not feasible under the constraints of building codes or nonprofit museum funding. Instead, a  restaurant was serving hot chocolate during the triangle-thon, which got underway at 6:54:32 p.m. Eastern time.

"That is the part that has me the more excited than anything -- that there are over 2,000 people who think math is cool," said Lawrence. "The other thing that's really cool is that not only have we gotten emails from al lover New York City and the country, but we've gotten emails from all over the world, from people who were wishing we would simulcast it somehow, so people can participate in some way."

Unfortunately, the nonprofit museum doesn't have the funds for simulcasting, though social media probably will take care of that all by itself.

The museum was the brainchild of Glen Whitney, who was chagrined to find out that an obscure math museum on Long Island had to close its doors, said Lawrence. He, Lawrence and a handful of other mathematically obsessed folks got together monthly and started planning for a larger, more elaborate affair. When they got an invitation to participate in a 2009 World Science Festival, they quickly set up an exhibit styled after a carnival midway. Soon, that became a traveling show.

"Really, that was a proof of concept for the museum, because that was hands-on math exhibits," Lawrence said. "We had 4,000 people show up the first day it was on the street in June 2009, and hundreds of thousands -- I think over a half-million people -- have seen it as it's traveled the country. And we raised a lot of money from that exhibit, because a lot of people came and saw their children at that exhibit and said, wow, you're changing the way my kid looks at math. … So we raised \$23 million on that proof of concept, that exhibit."

Today, if you come through the door (with its pi-shaped handles) of MoMath, you'll see a square-wheeled tricycle that rides smoothly over a track designed to accommodate it, designed using relatively simple math.

"That's actually the only exhibit that was repeated exactly from our traveling show in the museum here because people just love it so much," Lawrence said. "Everything else we did in the museum we did brand new. The whole museum is designed from scratch."

There's even talk of a MoMath West – somewhere in California. Whitney is a graduate of UCLA, and still has ties there.