Necessary Mathematics for solving problems

Hi friends I want some good documentation on the necessary mathematics which is required to solve the questions in the contests. It would be great help if anyone can suggest some link on number theory and other important topics.

This link helped me a lot:

Maths:

1 Like

http://discuss.codechef.com/questions/7412/help-in-combinatorics

http://discuss.codechef.com/questions/23229/how-to-start-off-with-mathematics-required-for-codechef-problems