Want to learn mathematics? Start with geometry.
Re: girls and maths: my wife, who is an aptitude test whiz and beats me at most analytical stuff, prefers physics and biology over maths (and can do/learn both of them better and faster than me). I have some guesses on the cause... I think maths (at the non-genius level) requires an element of stupidity or slowness, and perhaps certain small mental "disorders" such as OCD and paranoia. A while ago, Jerry Monaco wrote that he liked the way my thought process seems to work -- which was very kind of him -- and I think what he liked was perhaps the sort of plodding, slow, obsession over minutiae, style... which I think is also what made me decent at maths, and more importantly unafraid of it.
In most other spheres you are required to (and celebrated) for big thinking, quick and smart conclusions -- a sort of chess-playing intelligence: the ability to whittle away dead-end paths instinctively (and intelligently) to arrive at a best fit answer in the shortest time. And this is a valuable skill for the real world (something women have to deal with more than men do).
So, in speculative summary: (a) women are discouraged to study maths or science. (b) science and the soft sciences (from biology on), as opposed to [good(*)] maths, relates to the real world which women deal with and are more concerned about, (c) maths learning and use seem to benefit from a particular sort of mental behaviour, and unsurprisingly these traits such as OCD or autism are more prevalent among men than women.
This is all very idle speculation of course, and some of it stuff I would even strongly contest outside a left forum!
--ravi