Today is International Pi Day, not to be confused with National Pie Day, which was Jan. 23.
Only one thing really matters in discerning the difference: pie is finite.
Among those who know of pi's infinitude, most, I’d guess, still don’t know quite what to make of it. Its simple definition is “the ratio between the circumference and diameter of a circle,” a number that literally never ends and begins 3.14159... thus, 3/14.
That’s the day physicist Larry Shaw established the first Pi Day 25 years ago at the Exploratorium in San Francisco, where there is a parade today to honor it. Pretty certainly, the parade will come to an end at some point.
Here's another site, Project Mathematics, dedicated to the understanding of pi
Exploratorium’s site suggests some other hands-on pi activities, one of which is described below:
“You will need a circular object, string, scissors and tape. Carefully wrap string around the circumference of your circular object. Cut the string when it is exactly the same length as the circumference. Now take your “string circumference” and stretch it across the diameter of your circular object. Cut as many “string diameters” from your “string circumference” as you can. How many diameters could you cut? Compare your data with that of others. What do you notice?
“This is a hands-on way to divide a circle’s circumference by its diameter. No matter what circle you use, you’ll be able to cut 3 complete diameters and have a small bit of string left over. Estimate what fraction of the diameter this small piece could be (about 1/7). You have “cut pi,” about 3 and 1/7 pieces of string, by determining how many diameters can be cut from the circumference. Tape the 3 + pieces of string onto paper and explain their significance."
There will not be a test on this.
Photo of Larry Shaw leading the Pi Parade, courtesy of the Exploratorium