You guys know what pi actually is, right? If you’re digging back to old memories of geometry class, stop right there.
Pi is a real thing in real life. It means that the distance around a circular thing is a little more than triple the distance from side to side. This knowledge can help you solve a bunch of problems that are only tangentially related to mathematics.
Example: with pi in mind, you’ll always be able to eyeball the right amount of wrapping paper or ribbon for a gift. Or the amount of yarn it will take to knit a row of your scarf (about three times the width of the scarf, plus a little bit, because each stitch is a roughly circular loop of yarn). If you’re going to run a 1km long loop of road, you can guess that the shortcut from side to side is roughly a third of a kilometre. That’s pi. Here’s a visual explanation:
So what’s the deal with the greek letter and the 3.1415926535… kind of number? Well, “three times plus a little bit” is an approximation. If you want to measure it a little more precisely, you can get out a measuring tape and a circular object. My coffee mug is 8.7 centimeters across, and 27.9 centimeters when I measured with a tape measure around the rim, giving us a ratio of 3.2 (I got that by dividing 27.9 by 8.7, which you can just type into google if you don’t have a calculator).
With a more precise measuring tool, we would come up with a number somewhere around 3.14. With very precise tools, and if my coffee mug is really perfectly circular, we might get something more like 3.14159. This number fascinates mathematicians because you can keep measuring—or, with a computer, calculating—and never get a precise answer. And that’s why the Greek letter π is used in mathematical equations: it means that number, which we can’t fully write out.
If you want to know how much braided pie dough it will take to cover the crust of your next baked pie…it’s three times the diameter plus a little bit.