You Guys Know What Pi Is, Right?

Happy Pi Day! What is pi? If you’re returning to old memories of geometry lessons, stop right here. Pi is the real thing in real life. This means that the distance around a round object is just over three times the distance from side to side .

Know this and you can always find the right amount of wrapping paper or ribbon for a gift. Or the amount of yarn needed to knit a row of your scarf (about three times the width of the scarf plus a little because each stitch is roughly a round loop of yarn). If you are going to run a roundabout that is a mile long, you can assume that the shortest side-to-side path is about a third of a mile. This is pi. Here’s a visual explanation:

So what’s the deal with the Greek letter and number 3.1415926535 … like? Well, “three times plus a little” is a rough estimate. If you want to measure it a little more accurately, you can get a measuring tape and a round object. My coffee mug is 8.7 centimeters across and 27.9 centimeters when I measured the rim with a tape measure, which gives us a ratio of 3.2 (I got this by dividing 27.9 by 8.7, which you can simply enter into Google if you don’t have a calculator).

With a more accurate measuring instrument, we would get a number around 3.14. With very precise instruments and if my coffee mug is really perfectly round, we could end up with something like 3.14159. This number fascinates mathematicians because you can go on measuring – or, using a computer, calculate – and never get an exact answer. This is why the Greek letter π is used in mathematical equations: this is a number that we cannot write out completely.

So enjoy your Pi Day. And if you want to know how much wicker pie dough it will take to cover your pi-Day pie crust … that’s three times the diameter, plus a little.

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