@mister kitten,

mister kitten;150519 wrote:Rational numbers as numbers that make sense, I thought. I'll go look it up.

Well, it's about the same thing. But technically, it's the ratio/fraction idea.

---------- Post added 04-11-2010 at 04:09 PM ----------

mister kitten;150519 wrote:

Irrational numbers as numbers like pi or the square root of 2

Indeed, except that pi is also transcendental, whereas the square root of 2 is just irrational. And this is because the square root of two is an algebraic expression with a finite number of operations. (In this case, one). Pi can't be written so simply, to say the least. It's a strange number, this mother of curves.