TITLE: Books for maths olympiad
QUESTION [6 upvotes]: I want to prepare for the maths olympiad and I was wondering if you can recommend me some books about combinatorics, number theory and geometry at a beginner and intermediate level. I would appreciate your help.

REPLY [2 votes]: If you're looking for a good Geometry book, you can check out Evan Chen's book, Euclidean Geometry In Mathematical Olympiads.  There are no prerequisites to the book; all you need to do is know how to read proofs.  A PDF of the book is $28:
http://www.maa.org/press/ebooks/euclidean-geometry-in-mathematical-olympiads
As a sample, here's a free PDF of chapter 2:
http://www.maa.org/sites/default/files/pdf/ebooks/pdf/EGMO_chapter2.pdf