Write 9^0, 9^3, and 9^-2 in order least to greatest

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.