hello there, lets say we are talking in Newtons, the unit of force. 1kN = 1 x10^3. using the button that is second to the right on the bottom of your casio calculator is very useful. So what is 1MN? capital M stands for mega so that would be 1 x10^6 . All these powers are in page 45 of your tables book so u can access it any time during the exam.
I think the only things that you have to remember are the standard SI units. Like for distance, its metres, for time its seconds, for speed its m/s, for volume its m^3......it always comes back to the standard SI units which are on page 44 of the tables. That page is your reference point for every calculation you're faced with.