It may be helpful if you state your mathematical background, though I'm guessing that, if you had taken any proof-based math course, you wouldn't be asking this

It may be helpful if you state your mathematical background, though I'm guessing that, if you had taken any proof-based math course, you wouldn't be asking this. I recommend The Art of Problem Solving I and II. On the one hand, they're intended for (mathletic) middle and high-schoolers. On the other hand, some of their problems are quite challenging, and much of the material therein is what my school teaches in its intro discrete math courses since very few students learned it in middle and high school. http://www.artofproblemsolving.com/Store/contests.php http://www.artofproblemsolving.com/Store/contests.php