In number theory, I know GCD, LCM, remainder theorem and other simple things. I think these are not enough for me to solve problems in number theory. So I want to learn more about it. I hope someone can show me some ways to improve my skill in Number theory? You can give me a source of knowledge and problems in Number theory.
Thank you very much for reading.
There is something I would recommend to everyone: http://projecteuler.net/
There are more than enough different problems (mostly of mathematical nature) that require some programming skills to get the answer. I guess at least half of them are number-theory-oriented. Also, you can earn achievements and have no time control (conditions are perfect).