I will put  useful contents for studying mathematical olympiads in this page.

My problem sets

LTE Challenge Problems

100 Combinatorics Problems

100 Functional Equations Problems

150 Geometry Problems

100 Inequality Problems

100 Number Theory Problems

1220 Number Theory Problems

100 Polynomial Problems

50 Trigonometry Problems

Number Theory Books:

Number Theory Structures, Examples, and Problems – Titu Andreescu and Dorin Andrica

An Introduction to Diophantine Equations – Titu Andreescu, Dorin Andrica, Ion Cucurezeanu

104 Number Theory Problems – Titu Andreescu, Dorin Andrica, Zuming Feng


The following are free books which can be downloaded from this website:

Number Theory – Naoki Sato

Elementary Number Theory – W. Edwin Clark

Numbers and Curves (book draft, Springer, 2001) – Franz Lemmermeyer

Algorithmic Number Theory (web draft, 2002) – S. Arun-Kumar

Elementary Number Theory: Primes, Congruences, and Secrets – William Stein
 250 Problems in Number Theory – Waclaw Sierpinski