Math, iteration, and perfection.

Just wait 'til you learn about integrals! They're even more exciting :)

And cardinalities of infinite sets are cool.

Did you know not every infinite set of numbers has the same magnitude? (Informally, "they can have a different number of numbers.")

When I first understood Cantor's diagonalization argument, it blew my mind. It remains one of the most clever pieces of reasoning I've ever seen.

If you like that, check out the way to derive the golden ratio with continued fractions: http://en.wikipedia.org/wiki/Golden_ratio

Seems like he discovered Riemann's hypothesis.

> perfection (or in math terms, infinity)

Seriously?