If I decide to try to get alternative certification as a teacher, I will most likely need to take the Praxis II Mathematics subject exam, which is another one by ETS (like the SAT, GRE, etc.) Some states (like Texas) don't take this, and some states (like Colorado) take either this or their own in-state exam, but many states do take the Praxis.
So, out of curiosity, I downloaded a complete sample exam and took it. It is on paper (it's not one of those computer-based tests), 50 questions long, and you have two hours for it.
I won't say that it was trivial. You do need to know math in order to do well on it - at least high school math, and some college math to seal the deal. (I think I actually could have passed this when I graduated from high school, but most people wouldn't.)
I finished with about 20 minutes to spare and got 46 of the questions right, for an adjusted score of 184 (out of roughly 200). I would need a 156, which on this test corresponded to getting 32 questions right, to meet Colorado standards.
So I do feel confident that I can pass this exam without any additional study.