Monday's Pi Day -- the celebration of a number

Liam Ford

Tribune reporter

10:10 AM CDT, March 13, 2011

Monday is Pi Day — a day to celebrate a number with desserts, numerical recitations and hot-dog throwing.

Pi, the number that expresses the ratio of a circle's circumference over its diameter, was first calculated in ancient times, and sometimes is called Archimedes' Constant, for an ancient Greek mathematician who calculated an approximate value for the number. It's believed to be a number with no endpoint, although its digits start with 3.14159. Thus, March 14, or 3/14, for Pi Day.

The first Pi Day was celebrated in 1989 at the San Francisco Exploratorium, whose staff celebrates most years by walking in a circle around a "Pi shrine" a little more than 3 times.

And these days, the celebration has spread around the world, and math teachers, students and other self-proclaimed math fans amused or intrigued by Pi celebrate the number.

At Morgan Park Academy, a pre-K through 12th grade school on the Southwest Side, every one of the six math teachers, along with teachers in the lower grades, will focus on Pi in class, said the math team leader, James Kowalsky. In his geometry class, Kowalsky in the past has had students cut cardboard circles multiple times to fit them into squares, which allows students to calculate the area of the circles without using Pi.

In an after-school Pi event at Walter Payton High School, students will throw hot dogs on a floor marked with evenly spaced parallel lines. Why? Because the proportion of hot dogs that cross the lines when they fall works out to be approximately 1 over Pi, said Payton mathematics chair Paul J. Karafiol.One highlight of many Pi Day events is a competitive recitation of the numerous digits of Pi, which modern computers have calculated to a trillion deciminal places. At Morgan Park Academy, the record is 312 digits. The DuPage Science Fiction Society has had someone recite more than 100 digits, and a Payton student who's now at Yale University remembered a mind-blowing 500 digits.But those unacquainted with Pi might be more drawn to what's usually a big feature of the number's celebration: pie.The DuPage group was holding its Pi Day at a Bakers Square pie house on Sunday. Morgan Park Academy students bring in pies to share at lunchtime. And at Payton, with each digit of Pi that a student's able to recite beyond the first few, their piece of pie gets a little bigger — by one degree, measured with a protractor, Karafiol said.