Pi Day or Pie Day?

     Originally begot by Archimedes of Syracuse at around 250 BC, this mystical number was also discovered by both Chinese and Indian mathematicians. It was considered an irrational number close to 22/7 before the Madhava-Leibniz Series was discovered in India. Trigonometric functions are repeated in two times this number. The 14th of March each year is a day celebrating this number since 1988. Maybe Albert Einstein was so great at math because he was born on 3.14.

     If you are thinking about pi, you are on the right track. We cannot measure the circumference of a circle or the volume of a sphere without knowing pi. The significance of pi makes it the ancestor of geometry and calculus. 

The Ancient Method of Calculating Pi

     How did people discover this special number? You may generally use the formula of  circumference over diameter to estimate pi. But back in time, Archimedes used the method of exhaustion to approximate the value of pi. First, he made a circle with a radius of ½ and the circumference therefore would be pi. Then, he drew a polygon inside the circle. As the number of sides increases, the perimeter of that polygon approaches closer to the circumference of the circle, which is pi. Finally, after he calculated the perimeter of the polygon (shown in the  procedure below), Archimedes derived the formula of acquiring the perimeter this polygon — n*sin ϴ. The Chinesemathematician Zu Chongzhi also used a similar method.

The Pi Day

     The first Pi Day Celebration was first held at the Exploratorium by physicist Larry Shaw in 1988. The Exploratorium marched around a circular space and had fruit pies. It still holds Pi Day Celebration. On March 12th, 2009, The House of Representatives in the US officially recognized 3.14 — the Pi Day — as a national holiday. After that, many social media and websites started to hold celebrations of Pi Day. For Example, Google Doodle changed its logo on 3.14, 2010.

Pi Day Celebrations 

     Many math teachers also hold Pi Day celebrations every year. Some of the top options are competing in Pi recitation, walking around the circular spaces, and consuming pie in class.Teachers encourage students to learn and love Pi, and also the whole subject Math. One of the most popular ways to celebrate Pi Day is to bake pies and eat pies. Carrot pie, apple pie, and blueberry pie are the top choices. Here is a delicious recipe of “Triple Berries Pi Day Pie.” (Kitchens, Pillsbury. “Triple Berry Pi Day Pie.” )


3 refrigerated pie crusts (from 2 boxes Pillsbury™ refrigerated pie crusts), softened as directed on box

1cup sugar

5tablespoons cornstarch

2tablespoons quick-cooking tapioca

1/4teaspoon salt

3cups fresh or frozen (thawed and drained) blackberries

2cups fresh or frozen (thawed and drained) raspberries

2cups fresh or frozen (thawed and drained) blueberries

1tablespoon milk

2teaspoons sugar


  • – Heat oven to 450°F. Unroll 1 crust in an ungreased 9-inch glass pie plate. Press the crust firmly against the side and bottom. Trim along the edge. Set aside.
  • – Unroll 1 crust on the work surface. Using small number-shaped cutters, cut out numerals representing pi to as many digits as desired (for example, 3.14159265). Set aside.
  • – In a large bowl, stir together 1 cup sugar, the cornstarch, tapioca and salt; gently toss with berries. Let stand 15 minutes. Spoon into a crust-lined pie plate.
  • – Unroll 1 crust on the work surface. Using a small sharp knife, cut the pi symbol in the center of the crust. Place crust over filling. Wrap excess top crust under bottom crust edge. Press edges together to seal; flute. Brush crust with milk; arrange numerals around edge of crust. Sprinkle crust with 2 teaspoons of sugar.
  • – Place pie on middle oven rack; place large cookie sheet on rack below pie plate in case of spillover. Bake for 15 minutes. Reduce oven temperature to 375°F. Cover edge of crust with strips of foil to prevent excessive browning. Bake 40 to 45 minutes longer or until the crust is golden brown and the filling is bubbly. Let stand 2 hours before serving.



  • – Kitchens, Pillsbury. “Triple Berry Pi Day Pie.” Pillsbury.com, 13 Mar. 2013, www.pillsbury.com/recipes/triple-berry-pi-day-pie/e1a7c76c-cb8e-4a9b-97b7-a0b62aca45ad. 
  • – “Pi Day.” Wikipedia, Wikimedia Foundation, 27 Jan. 2021, en.wikipedia.org/wiki/Pi_Day.
  • – Holland, Brynn. “What Is Pi Day?” History.com, A&E Television Networks, 11 Mar. 2017, www.history.com/news/where-did-pi-day-come-from#:~:text=March%2014%20marks%20Pi%20Day,%E2%80%94the%20perfect%20pi%2Dincidence.
  • – “Pi.” Wikipedia, Wikimedia Foundation, 7 Feb. 2021, en.wikipedia.org/wiki/Pi.
  • – Mathmaticsonline. “How to Calculate Pi, Archimedes’ Method.” Youtube, www.youtube.com/watch?v=DLZMZ-CT7YU.
  • – “A Brief History of Pi (π).” Exploratorium, 14 Mar. 2019, www.exploratorium.edu/pi/history-of-pi.