If you think of an exponent as signifying repeated multiplication, the rules of exponents may be easier to remember. The exponent tells you how many times the base is a factor in the product.
Consider multiplication:
Consider division:
This may help you see that a positive exponent in the denominator is equivalent to a negative exponent in the numerator (and vice versa).
I always remembered it as the 's' (for supplementary) is farther than 'c' (for complementary) in the alphabet just like 180 degrees is farther than 90 degrees
so supplementary is 180 degrees complementary is 90 degrees