What is Pi Day?

March 14 is celebrated as Pi Day across the world! Dig into this holiday with us to learn about its origin and how to celebrate.

What is Pi?

Pi (pronounced like “pie”) is the Greek letter for p, represented by this symbol: π. In mathematics, pi (π) represents an irrational number with an approximate value of 3.14. 

Circle graphic from PiDay.org

Pi is the ratio of the circumference of any circle to the diameter of that circle. 

If you were to measure the diameter of a circle, using a ruler to determine the length from one side of the circle to the other through the center point of the circle, and multiply that length by 3.14 you will calculate the circumference, which is the length of the circle’s outside border.

• No matter the size of the circle, the ratio of the circumference to the diameter of that circle is 3.14
• Babylonians and Egyptians are believed to have been aware of the significance of pi back in 2000 BCE. 
• Pi is an irrational number, meaning that it never really ends. For simplicity, we round the number up to 3.14.
• Computers have calculated the first 62.8 trillion digits of pi. 
• The Guinness World record for most Pi decimal places memorized by a human goes to Rajveer Meena. He was able to recite 70,000 digits of Pi! 

Now that we’ve explained the basics of pi, let’s see what makes this holiday so sweet!

History of Pi Day

Mehaffies Dutch Apple Pie

Pi Day is celebrated annually on March 14 (3.14) all around the world! 

The first Pi Day was founded in 1988 by Larry Shaw and hosted at the Exploratorium, the science museum where he worked in San Francisco. He celebrated with circular parades and pies! In 2009, the U.S. House of Representatives officially recognized Pi Day as a national holiday. 

Pi Day is often celebrated with pie, a natural choice since pi and pie are homonyms pronounced the same way. Plus, pies are round just like the circles for which pi is a calculation ratio, creating opportunities for delicious math problems!

March 14 also happens to be the birthday of world-renowned mathematician Albert Einstein.

Celebrating Pi Day with Mehaffies Pies

The most delicious way to celebrate Pi Day on March 14 is with your favorite pie! Mehaffies Pies in Dayton, Ohio accepts call-ahead orders and will have a variety of whole pies and pies by the slice for purchase on Pi Day, March 14, 2022 from 8 a.m. to 5 p.m. (or while supplies last).

Choose from fruit pies including Fresh Strawberry and Apple, Banana Cream pies, Sugar Cream Pies, Peanut Butter Pies, Key Lime Pies, No Sugar Added pies and more! 

You can also cut some “pi” before you eat your pie with this activity from Exploratorium.

• • Measure the circumference of the pie by placing a string around the outer edge of the pie crust.
  • Cut the string. 
  • Now use the same string you cut to measure the diameter of the pie (from one side to another from the center point). 
  • Cut the string the length of the diameter and repeat.
  • You’ll find that you cut 3 diameters and a little extra from that circumference string.
  • You just cut pi! 
    • 3.14 diameters = circumference
  • Now reward your effort and dig in!

For more Pi Day fun, check out fun resources from the official host of Pi Day, Mometrix. 

Call Mehaffies today to pre-order your favorite pie for Pi Day March 14!

Cutting Pi Video © 2020 Exploratorium.