Yellow Pigs Day

Yellow Pigs Day

YP Day is held on July 17th. As always, we love having alumni return for the festivities. We don’t love surprises though (well, we do, but not the kind that we have to feed and house), so please let us know a few weeks in advance if you’re planning to come visit.  Here’s some of what you can expect if you come to visit:

  • All the nostalgia of being on Hampshire’s beautiful campus again, along with some surprise at how much has changed
  • Kelly’s A Mathematical and Social History of the Number 17
  • A vigorous student-vs.-alumni Frisbee match
  • A chance to join the nightly problem set
  • Carols and cake!

Some things you can’t expect: materials or time to make YP shirts (please make & bring your own); transportation to or from campus; that the students will know the tune to your favorite YP Carol; accommodations if you decide to come at the last minute; the discovery of any odd perfect numbers.


There are a lot of ways to get to us including, but not limited to, walking, flying, training, jump-roping, driving, and skydiving. If you choose one of these methods of transportation, hopefully the following information will be helpful.

See you there.

About Yellow Pigs Day (July 17)

Yellow Pigs Day is an annual celebration associated primarily with the Hampshire College Summer Studies in Mathematics, a summer program in math for talented high school students. We use it as an excuse to gather up five decades of alumni for cake and Yellow Pig Carols. But it’s also a celebration of a certain approach to the doing and learning of mathematics, where joy, humor, and interestingness take the place of formulas, drills, and multiple-choice tests. Furthermore, it’s a great opportunity to show off how much you know about the number 17.

YP Day is also celebrated around the world by other groups of people: satellite cake-and-carols parties pop up in locations with a nontrivial alumn density, like other summer programs Mathcamp, PROMYS, Ross, or undergraduate institutions like MIT, U Chicago, and Stanford. This 1982 article from the Crimson describes a campus strewn with seventeens… those were the days.

A small Internet subculture of bloggers-interested-in-odd-holidays has recently learned about Yellow Pigs Day, and there’s evidence that non-mathematicians are now celebrating along with us — at least for the cake. Be careful learning about YP Day from these sources, as scarcity of information has led to speculation and fabrication in re who we are and what we do. If you want to learn more, you can get it straight from the pig’s mouth.

Furthermore, be careful of yellow-pig-branded apparel and sundries. Robots, the unscrupulous, and unscrupulous robots scrape the web to take our images and logos and sell them on mugs and pencil cases through sites like Zazzle and CafePress. We do not see a cent of those profits, and we’d much prefer you make your own Yellow Pig Shirt like we do. If you’re looking for a way to ensure that Yellow Pigs Day will always be there, please give a gift to HCSSiM. We appreciate it loads.

*not Yellow “Pig” Day — if you’ve seen Kelly’s collection, you know that the plural is more than appropriate