What is Pi?
What is pi? Simply put, pi is the relationship between a circle’s diameter and circumference. Pi is represented by the Greek letter “π” and is approximately equal to 3.14.
To back it up a bit, the circumference of a circle is the length of the edge of a circle. The length of the diameter is the distance from one point of the circle’s edge to another. Keep in mind that the distance runs through the center of the circle! The radius is half of the diameter, so it’s the distance from the center to the edge of a circle. Feel free to check out a picture of this below!
Have you ever wondered how the diameter of a circle relates to its circumference? It turns out that a circle’s circumference is about 3.14 times greater than its diameter! So, a little over 3 diameters equals a circle’s circumference. We can represent this relationship with the equation C=πd, where C stands for the circumference of a circle, and d stands for its diameter.
Still a bit confused about just what pi is? Let’s break it down together!
A History of Pi
The concept of pi has been around for a long time and is well known. An influential person to calculate pi is a Greek mathematician named Archimedes. Archimedes is from 287–212 BC in an ancient city called Syracuse. While he concluded that pi was between 223/71 and 22/7, there were approximations for pi centuries before.
This number has gained attention from many around the globe. During the time of Archimedes, pi came from lots of geometrical data and estimating. It was more recently that mathematicians came up with non-geometrical ways to estimate pi. These discoveries couldn’t have been found if it weren’t for the mathematicians who helped develop the techniques used to calculate pi!
How Long is Pi?
It’s interesting that pi goes on forever, at least for its decimal expansion. Be careful because pi isn’t infinity since it’s less than 4, but it does have an infinite number of decimal places. You might have a bunch of questions like “Why?” or “Does that mean all calculators are wrong?”
Pi goes on forever because it’s an irrational number, which means that it cannot be represented as a fraction with whole numbers in the numerator and denominator. This doesn’t make calculators wrong, but they’re not completely accurate since they don’t use all the digits of pi. They only use and display a certain number of digits, so even calculators round when they use pi in math problems.
How to Approximate Pi
Finding pi can seem hard, but it’s cool because you can find pi outside your math homework! Following the steps below will help you find pi from items like a cup or small table, but make sure you're using a perfect circle … otherwise, this won’t work!
Find the circumference of the circle. You could do this using a tape measure or by tying yarn around the circle and measuring the yarn. Try to be as accurate as possible when measuring!
Then measure the diameter of the circle.
Take the circumference and divide it by the diameter (circumference/diameter)
What you got from step 3 should be around 3.14!
Didn’t get a number close to pi? There most likely was an error while following the steps, so try again and see what you get!
Here’s the circumference, radius, and diameter of a circle for reference:
Final Thoughts on Pi
Hopefully, you’ve now learned what pi is and how to find it! It takes time, so practice until you find that correct, neverending number! Still need help or support in other areas? Make sure to get in touch with a UPchieve tutor to work with you for free.