What is Yellow Pig's Day?

You are perhaps wondering what the Center of Math is doing posting about a holiday dedicated to yellow pigs. Was this meant for another blog? Is the Center of Math announcing that they're now the Center of Pork Artistry? To answer those questions, no, and not in the foreseeable future.

Yellow Pig's day is actually a celebration of the number 17. In the 1960's, a pair of math students at Princeton were discussing the many properties of 17, and decided that there should be a day to celebrate it. Ultimately the date they decided was July 17th! Thus, Yellow Pig's Day was born. Why Yellow Pig's Day? One of the students discussing 17 decided that the mascot of the holiday should be a yellow pig with 17 eyelashes, 17 teeth, and 17 toes.

Here are some of the properties of 17 that make it worthy of a mathematical holiday:

-17 is the smallest number that can be written as the sum of a cube and a square in 2 different ways (8+9=17 and 1+16=17)

-It is also the smallest number that is the sum of two powers of 4 (1+16=17)

-17 is the minimum number of givens in a Sudoku puzzle for the puzzle to have a unique solution

-In Italy, 17 is a lucky number. In Roman numerals, 17 is written as XVII, which is an anagram of VIXI, which means 'my life is over' in Italian.

-Depending on how you look at it, 17 is either the most random or the least random number. In a study in which respondents were asked to pick a random number between 1 and 20, 17 was the number that was selected the most. Is it the most random because the most people decided it was the most random? Or is it the least random because the most people chose that number?

-17 is the only prime number that is the sum of 4 consecutive prime numbers (2+3+5+7=17), which is possible because 2 is the only even prime number and the smallest prime number. The sum of any other 4 consecutive primes will be even, and thus won't be prime.

-And, finally, as all ABBA fans know, 17 is the age of all young, sweet Dancing Queens

There is no one way to celebrate the holiday, but this haiku (a poem with 17 syllables!) should offer a good starting point:

Spend time with some friends,
Hug a mathematician,
And have a good time!