Sunday, March 15, 2015

In Honor of Pi Day: Deriving Pi from a Pie

Yesterday was Pi Day (and I intended to write this last night, but overslept in my evening nap), the day on which the abbreviation for the date (3/14) consists of the first three digits of pi (3.14).  And yesterday was a very special Pi Day, on which the abbreviation for the date including the year (3/14/15) consisted of the first five digits of pi (3.1415).

Some people like to incorporate pie (the pastry) into the celebration of Pi Day.  I think that if you include pie in your Pi Day, before you eat the pie, you should do the following:

1. Get a tape measure, and measure the circumference of the pie. 

2. Measure the diameter of the pie. 

3. Divide the circumference by the diameter.  

Thus you will have derived pi from a pie.  

(I imagine that I am not the first person to think of deriving pi from a pie, but it makes me feel clever, so I am putting the idea on my blog.)

I tried this exercise myself to see how well it works.  I didn't have a pie, but I measured a roughly pie-sized circular plate.  I got 3.11, which is within about 1% of the correct value.