On 3.14 this year, I sent an email to the team wishing everyone a Happy Pi Day. For fun, I threw in a little brain teaser: what other day of the year could stand in and serve as Pi Day and why?

I’m so glad I chose to do that. What a delight! I didn’t expect the responses I got along with everyone’s reasoning. Note to reader: if you want to play along, stop here to think about your answer. When you’re ready, continue reading to learn about the variety of answers we generated.

When I first thought of it, I knew the fraction 22/7 was sometimes substituted as an approximation of pi. So if we think about the way dates are expressed in Europe and other parts of the world, July 22nd could work as an alternate Pi Day.That’s 22/7 in Europe and 7/22 in America. So…what did my teammates think?

I knew I was in for a treat on Pi Day this year after reading the first few replies, which went in directions I didn’t anticipate at all. The 314th day of the year is November 10th, so 11/10 could stand in as an alternate for Pi Day. And June 28 is 2pi, which could also work as a substitute Pi Day though perhaps with the explanation that we’ve doubled the famous ratio of a circle’s Circumference divided by its Diameter.

There are 7 of us all together at Building 21, and the only team member who came up with the answer I was expecting (22/7 or 7/22) is the only other team member who has spent time living and working in Europe like me! Isn’t that fascinating? It made me wonder about the role traveling plays in education.

The most adorable reply I received was that Thanksgiving Day could also be Pi Day since people eat more pi(e) on this day than any other! 🙂 As I thought about it, there’s actually an aspect of this answer that makes it especially valid. Π as a number is infinite, non-repeating and therefore inexact. That’s why we use the symbol π to represent this number, because the symbol captures something that the use of numbers cannot– at least not easily. We typically chop the decimal part after two digits and use 3.14 as an approximation of pi. Thanksgiving Day occurs in the US every year on the 4th Thursday in November, but the exact date of that Thursday changes every year. We know it’s always on the 4th Thursday in November, and we always call it “Thanksgiving Day”. Well “Pi” works the same way. For every circle, pi is always the quotient or result of dividing the circle’s circumference by its diameter, regardless of those exact dimensions. Whenever we do that, we get the same, fascinating little number called “pi”. Regardless of the exact date in November, we always call the 4th Thursday “Thanksgiving Day”.

Thanks to my teammates for participating in this marvelous and fun little experiment!