Anytime you combine an an adjective with a noun to collectively modify another noun, such as numerical phrases like "a ten-page report" or "a one-horse town", you need a hyphen.
It's called compound adjective. The adjective "ten-page" modifies "report". It also applies to phrases like "high-quality quiz" and so forth.
You hyphenate when you combine...
* an adjective with a noun, as in the examples above ("one-horse town" or "middle-class neighborhood")
* an adjective with a participle, as in "tight-lipped man"
* an adverb not ending in -ly with a participle, e.g. "much-needed addition"
* an adverb not ending in -ly with an adjective, e.g. "little-understood rules" (like this one?)
That's according to the Chicago Manual of Style.
P.S. You don't use a hyphen when adverb ends in -ly, e.g. "a highly paid staffperson", which I am sure you all are.
I did some edits here.