Answer:
0.0405
Explanation:
10^-2 is the same as 1/100, so if you multiply 4.05 x 1/100, you get 0.0405.
Another way to think about it is by looking at the exponent -2. You need to move the decimal point 2 spaces to the left -- and add zeroes to any spaces that don't already have numbers.
So if you start with 4.05, and move the decimal one space to the left, you get 0.405, and then you move it one more space, and you get 0.0405.