It depends on what the question is asking for... If the problem looks like this: (-16m)^2 would equal 256m^2. Since they want the numerical coefficient, the answer would be 256.
To the second power means that you're multiplying each number/variable within the parenthesis two times. In essence, we have (-16m)^2 = (-16-16mm). -16-16=256 and mm=m^2. We get 256*m^2. Good luck!
