It's so straightforward. I've seen one nontrivial problem that appeared on an AP calculus exam before and it was actually a really fun one. Tricky limit problem.
Essentially it was evaluating the limit of f(f(x)) at some point, where the graph of f was shown. The trick was that if you just fed the limit of f(x) into f, you'd get the wrong answer, and if you tried to take the limit of f(x) as x approaches the limit of f(x), you'd also get the wrong answer. Instead, it ended up being a one-sided limit in the second iterate. Great problem. No calculation, just pure limit intuition.
