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.