I think problem solving strategy is interesting book exactly for teens. It doesn't need deep mathematical background. However If its math is hard for startup, you can find some interesting and small discrete-mathematical book and start reading them, then switch to this book. I read it when I was in high school and this book motivate me for making stuff in CS.
P.S: I think small interesting book in discrete-mathematical area for teens, depends to country culture and its language, I know good one in my language, but I don't know any good one in other countries.