The order is 9^-2, 9^0, 9^3.
When an exponent is negative, the term can be moved from the numinator to the denominator (or vise versa) to change the negative exponent to a positive one. So 9^-2 becomes 1/9^2 = 1/81.
Anything to the 0th power becomes 1. So 9^0 is 1.
Finally, 9^3 is 729.
