03.14.14 // Yum, Pi Day!

Written by Adrienne M. Roehrich, Manager of Editorial Services


Image from Wikimedia Commons.

Pi Day, March 14, or 3.14 has been gaining popularity over the past few years. There’s a counter movement to promote Tau Day as well. I love that a geeky mathy thing that everyone learns in elementary school is so popular. It’s also a great excuse to eat some pie!

Pi or π is the ratio of a diameter of a circle to its circumference. It is a mathematical constant and sometimes called a constant of nature. It is commonly given as 3.14159 (and next year we get to celebrate Pi Day to the fourth decimal place!) but is an irrational and transcendental number, with no common fraction representation and the decimal form being never-ending with no repeating pattern. Cool, right? (I love numbers!)

The history of π is also fascinating. Pi has been recognized for just about 4000 years and our earliest known determination of it was the Ancient Babylonians on a tablet, who recognized that the circumference of a circle was roughly 3 x the diameter, π = 3. Just about that same time, the Egyptians were also calculating pi, leaving behind the Rhind Papyrus as evidence.

In the early first millennium, both Archimedes of Syracuse, Greece and Zu Chongzhi of Baoding, Hebei, China, were using different methods to rigorously calculate pi. They represented pi in fractions, rather than decimals.

The Greek letter π was not actually used to represent this mathematical constant until the 1700s when it was introduced by William Jones and popularized by Leonhard Euler. Euler is well known for a number of theorems in mathematics and the angles used to specific the orientation of a rigid body called Euler’s angles.

Most recently, pi has been calculated to one trillion places beyond its decimal point. The accuracy of Pi Day varies, but many especially celebrate at 1:59 (am or pm). The most accurate celebration day in our lifetime will be 3/14/15 at 9:26:53.589, the likes of which hasn’t been seen since 1915 and won’t occur again until 2115.

Pi Day is often celebrated with pie! (What else?) So, the Venn Diagramm of Lovers of Pie and Lovers of Pi converge for the day. What kind of pie is appropriate for Pi Day? Any flavor will do, as long as it is round.

Besides eating pizza pie and following up with a dessert pie, what else can you do to celebrate Pi Day? There are tons of online Pi Day activity suggestions. Here are just a few resources:

You can also search for “Pi Day” and your city to see if there are local activities for you to participate in. In Seattle, for instance, The Seattle Children’s Museum has Pi Day activities starting at noon and the West Seattle Branch of the Seattle Public Library has activities starting at 3:14pm (of course!).

Image by Visual Merchandise Designer Amber Dawn Bushnell

Image by Visual Merchandise Designer Amber Dawn Bushnell

Should you want to make a pie on Pi Day, here is an Apple Pie Recipe.

Crust Ingredients:

Crust Directions:

  1. In a large bowl, sift together flour, sugar and salt. With a pastry blender or two knives, cut in lard until mixture resembles coarse crumbs. Mix together egg, vinegar and water, then add to flour mixture. Mix until dough is moist enough to form a ball.

  2. Wrap in plastic and chill for 30 minutes.

  3. Divide dough in half. On a floured surface, roll one half into a 12-inch circle. Press dough into pie plate. Crimp to form decorative border, then prick bottom with fork.

  4. Place in freezer while preparing pie filling. Makes one double crust pie.


Apple Pie Filling Ingredients:

Apple Pie Filling Directions:

  1. Preheat oven to 375ºF.

  2. Mix apples, flour, sugar and cinnamon. Stir gently. Pour into unbaked pie shell. Dab with butter and pour milk over filling.

  3. Roll top crust same as bottom and lift onto filled pie or decorate with woven lattice top. Bake 40-45 minutes. Filling for one pie.

Don’t feel bad if you miss celebrating Pi Day today. You can always celebrate Pi Day Approximation on July 22! What are your plans for Pi Day? Tell us in the comments!

This post appears concurrently at Double X Science.


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