micro (very small)
     microscope (tool for looking at very small things)

mono, uni (one)
     monorail (one-rail train)        unique (one of a kind)

non (no, not; also see un)
     nonfiction (not fictional; factual)

oct (eight)
     octopus (a sea animal with eight armlike tentacles)

pre (before)
     predict (to tell about something before it happens)

quad (four)