Is there good material for testing math skills?

I'm thinking abut something:
-All basic knowledge required to solve the puzzles are given beforehand, the same way textbooks use with their exercises
-In order to understand the basic knowledge it shouldnt require more than high school math.
-Variety of difficulty. From very easy to very hard.

Apparently the overall 'level of difficulty' is by textbook. Some are easier , some are harder.
It that's unexcapable, you could suggest two textbooks - one for the easy part, another for the hard part.

I expected 'concrete mathematics' was a good one. But then I was told its 'easy'. Its that accurate?