This may seem a bit weird, but I have always thought of numbers and letters having genders. 1 is female, 2 is female, 3 is male, 4 is female, A is female, B is male, C is female etc. I don't know why.
I have read that some people associate number with colours.
Oh, and they also have personalities. 9 is a bit of a pain. 4 is in love with 5. 3 likes 4, but 4 doesn't like 3, but they're stuck next to each other. 3 has a thing for 4 like the Claw did for Penelope Pit Stop.
Anyone else out there?