## Pi and the Circle

Pi ($\pi \approx 3.1416$) is probably the most popular among all the irrational numbers.  It is seen in almost all fields of mathematics and it often appears in places that you least expect it to be (like in birthday party perhaps?).

$\pi$ is the ratio of the circumference ($C$) of a circle and its diameter ($d$). That is, if we take a circle of any size, measure its circumference, measure its centimeter and divide them*, then » Read more