TITLE: Math for computer science?
QUESTION [13 upvotes]: Math for computer science?
I'm a computer science major and just completed linear algebra. Many courses are available to take now. Of particular interest: number theory and abstract algebra (Modern Algebra). Which one do you recommend? Is there any overlap between the two courses? Which one is more applicable to computer science? 
I would like to learn more, 
Thanks.

REPLY [3 votes]: As usual the answer is, it depends. If you go into a field like algorithms and end up wishing to do algorithmic number theory then surely, as the name implies, you need to know algorithms. If you go into cryptography, you'll also need number theory, as RSA and elliptic curve cryptography use a lot of it. 
However if you go into want to go into something like signal processing or coding theory and information theory, you'll be better off with abstract algebra. A lot of graph theory also has some algebraic components. 
On a final note, most number theory beyond the elementary level requires an understanding of groups, rings, and fields. Even one's understanding of elementary number theory can be enriched with a knowledge of group theory.
For a similar discussion see this, this, and this.