Answer: 16
Explanation:
A perfect square is basically some number multiplied by itself. For example, 4 is a perfect square because 2x2=4.
22 x 22 = 484 (under 500)
23 x 23 = 529 (over 500)
Therefore, the perfect square must be 484.
Subtract 484 from 500:
500 - 484 = 16
16 is the answer :)