I did not catch well, but i think you already got your answers. Let me explain. For the first part you got your notation right: for 0.0045 the correct scientific notation is 4.5 x 10^-3. Now the second part, the answer would be the first one, the notation that you are giving is the one who corresponds to <span>4.5 x 10^-2, the first option you have. Hope it helps</span>