1) David Blatner, ''The joy of π''
A mix; Maths, history of Maths and π
2) (my fav. one!) ''A briefer History of Time''- Steven Hawking and Leonard Mlodinow.
Ok, this is a simplified version of the famous book '' A brief History of time''.
A tip now; the first time you'll read something and you'll say ''oh that's hard...'', don't panic!, sometimes, in science you need to read 2 or 3 times some difficult parts... So...read a paragraph and don't give up. The next time you'll read it, you'll say ''Yeah, a piece of cake!'' BTW i love cakes...
Hope it helps! ^-^