I was reading about π (pi) today, and of course, went to wikipedia to read about it. One thing that I don't remember so clearly from math class (sad, since I was a mathematics minor....) was ...

Originally defined as the ratio between the circumference of a circle and its diameter, pi — written as the Greek letter π — ...

IN the first of these tracts Prof. Dedekind gives a theory of irrational numbers and of the arithmetical continuum which is logically perfect, and in form, perhaps, more simple and direct than any ...