The Greek letter π ("Pi", pronounced - at least in the UK - like "pie") when encountered in mathematics is usually used as shorthand for a pretty important number. This number can be defined in various ways, but arguably the simplest is "the ratio of a circle's circumference to its diameter." To put it another way, π tells you how many times bigger the circumference is than the diameter; or it's the number you get if you divide a circle's circumference by its diameter:
\[ \pi = \frac{C}{d} \]
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| Circumference, Diameter & Pi by T.Briggs is licensed under CC BY-SA 4.0 |
One way that π could be calculated is by measuring the diameter and circumference of a given circle and dividing the latter by the former. But one of the reasons we might want to know a value for π in the first place is that it is difficult to measure the circumference of a circle.
