I don't want to sound completely silly, but unless we're expecting people to take only a very brief glance at your personal statement, then wouldn't it be better to think more about the end of your statement, which will be the bit they're more likely to remember?
Unfortunately, I applied for a right mix of courses last year, so I didn't want to direct my personal statement completely in the maths direction. I did end up writing an additional statement, mainly about maths, and I started by commenting on a certain thing that people often percieved about maths, and went on to comment that although it was true, there is a lot more interesting stuff to maths as well. The additional statement worked very well with one uni, but apparently didn't with another [however, I stuffed up the interviews with that one
Another thought: won't a lot of people be applying for maths, and writing about it all? If you do that, then although you might display the fact that you find differentiation jolly fascinating, you won't really separate yourself from all the other maths applicants. I would suggest you write at least a bit of your statement about who you actually are, rather that just 'I want to do maths, offer me a place
I'm nice!'. When you tell them about yourself, you can say how you got interested with maths, and include all of the little things about you that not only make you you, but which make you good at maths.