On July 17th, we celebrate Yellow Pig Day, a whimsical and little-known holiday that originated in the world of mathematics. The story behind this peculiar celebration dates back to the 1960s at Princeton University.

Two mathematicians, Michael Spivak and David C. Kelly, were studying the properties of the number 17. During their research, they discovered that 17 had some unique and amusing characteristics. For instance, 17 is the sum of the first four prime numbers (2 + 3 + 5 + 7) and the only number that is the sum of three different primes in exactly three different ways (2 + 2 + 13, 3 + 5 + 7, 5 + 5 + 7).

Spivak and Kelly decided to create a fictional creature called the "Yellow Pig" to represent the number 17. They chose the color yellow because it was Kelly's favorite color and a pig because of the phrase "pig in a poke," which refers to buying something sight unseen, much like the mysterious properties of the number 17.

Since then, Yellow Pig Day has been celebrated annually on July 17th (7/17) by math enthusiasts, students, and educators worldwide. People often celebrate by solving mathematical puzzles, baking yellow pig-themed treats, or creating artwork featuring the Yellow Pig.

One of the most famous traditions associated with Yellow Pig Day is the recitation of the Yellow Pig Carols, a collection of mathematical songs and poems composed by Spivak and Kelly. These carols are filled with puns, jokes, and references to various mathematical concepts.

So, if you find yourself wanting to celebrate something a little different today, why not join in on the Yellow Pig Day festivities? Embrace your inner mathematician, solve a puzzle or two, and don't forget to wish everyone a "Happy Yellow Pig Day!"
2025-07-17T09:51:52.491Z