How much math do you have to know to be a programmer? I've heard you've gotta know shit like trig to work in C.
A version of that text was used in the Discrete Structures class I took.There's also one by the same name "Discrete Mathematics and it's Applications" but the author is K. Rosen.
Anyways, to piggyback on @Kosher Dill 's reply, one area of (discrete) math that might be most useful or practical is boolean algebra and how true/false works with various combinations of AND, OR, and NOT operators. That's useful for evaluating or simplifying complex expressions that have a True/False result.
The only other time math ever seemed necessary for CS/programming was for the computer graphics course I took. Because some of the transformation operations were expressed as matrices, the college's introductory course for matrix/linear algebra was a perquisite. Logical organization/thought is probably more important than the mathematical aspects most of the time.