Depending on your prescription, it should be pretty easy to see if your contacts are inside out or not, even without looking at the markings. Set the lens on the edge of your fingertip, and look at the profile of the lens. If the lens curls outward, then it is probably inside out. If the lens has a nice uniform curve, like if you were to slice a baseball in half, then it should be correct.

Another way to tell, clean the lens well and then put it in. If the lens is difficult to get in, won't stay in, or is uncomfortable, try it the other way, and compare.
Source(s):
5 years as a dispensing optician