# Pi Day 2021

Sunday, March 14

Morning, afternoon, or evening:

Pick up your fun Pi Day items — including the ever-popular pizza pi wheel — at MoMath: shop.momath.org/pi-items.

Don’t forget to set your clocks forward on Sunday, March 14, for the beginning of Daylight Saving Time.

11:00 am ET (New York): Start your morning off right with some eye-opening pi…

11:00 am ET (New York): “Roping Around the World”
Come test your intuition with a mathematical problem about a rope tied around the Earth.  Explore the counterintuitive solution with an engaging, hands-on activity.

11:30 am ET (New York): “Why don’t we celebrate Phi Day?”
Phi, also known as the Golden Ratio, is one of the most unique irrational numbers in all of mathematics.  Come learn about this fascinating number that shows up in all sorts of unexpected places, including a number of MoMath exhibits.  Then, discover how the number pi, in contrast, truly is more special and deserving of its own holiday and how pi transcends the basic rules of arithmetic.

2:00 pm ET (New York): Who needs high tea when you can have pi glee?

2:00 pm ET (New York): “Probably Pi?”
While it is impossible to write pi in its entirety, various methods exist to generate better and better approximations.  In this crowd-sourced experiment, we see how the law of large numbers lets us confidently approach pi by using probability.  By randomly dropping a needle onto a set of lines, we can converge on pi experimentally, without the need for direct measurement.  Come help us generate data to see how many digits of pi we can get — the more, the mathier!

2:30 pm ET (New York): “What is the value of Pi?”
Throughout history, people have tried to compute the exact value of pi.  Ancient Babylonians believed that pi = 25/8, Egyptians thought that pi = (16/9)^2 = 256/81, while the Indiana state legislature almost passed a bill in 1897 to legislate the value of pi.  We know now that pi cannot be computed exactly; join us as we use geometric constructions to find rational approximations.

6:00 pm ET (New York): Pi by night: BYOP…join Alex Kontorovich for an evening exploration — and bring your own (pizza) pi!
Join MoMath’s Distinguished Visiting Professor, Alex Kontorovich, for an exploration of pi.  What does pi have to do with circles?  How can we be sure that pi is bigger than three…or smaller than four?  How can the power of pi surprise us when we look at everyday household items?  And how can we use everyone’s favorite food to learn more about this amazing number?  Join us to find out…and bring your own pizza pi!  Click here to register for this evening session.

The following materials may be helpful but are not required:

• a pizza pie and a pizza wheel or knife — we will be both cutting and eating the pizza!
• a string, dental floss, or a thin strip of paper cut from the long side of a sheet of printer paper
• an assortment of cylindrical household containers such as a:
• tennis ball can
• tuna fish can
• soup can
• soda can
• water bottle
• thermos
• pasta canister (spaghetti container)

Make your own Pi Mobile and bring it to the “Pi by Night” event: we’d love to see your creation!

These are live-streamed events.  Occasional video recordings are made available for a fee at videos.momath.org.