The student is wrong because when you simplify 8^3 you get 512 (8*8*8) and when you simplify 8^-5 you get 1/32768 (you put a 1 over 8^-5 to make it a positive fraction, then you simplify 8^5 to 8*8*8*8*8 which would be 32768). When you multiply them, you get 512/32768. Since this is a fraction and the numerator is not more than the denominator, it is less than 1.