Question

The power output of a typical large power plant is 1000 megawatts (MW). Express this result in W, kW, and GW .

Answer 1

http://en.wikipedia.org/wiki/SI_prefix
By checking this site you will get ALL the prefixes that you're asking and more.
Mega (M) is ONE unit times a million, you have already a thousand, so you have a 1,000 x 1,000,000 = 1,000,000,000 watts.
Kilo (K) is ONE unit times a thousand, if you have 1,000,000,000 watts, then remove 3 zeros so you get 1,000,000 KW.
Giga (G) is ONE unit time a Billion, If you have 1,000,000,000 watts, then you already have a Gigawatt.
Check the site, so you'll see the variety of scales, they are better than to carry zeros or mention large numbers.

Answer 2

thank you!!