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 ...

Irrational numbers are numbers that cannot be expressed as the ratio of two whole numbers. This is opposed to rational numbers, like 2, 7, one-fifth and -13/9, which can be, and are, expressed as the ...