That's what they say, be sure to hit the important points/words -- I don't think long winded answers will help, and anyway there isn't much place for that
One question I had is if its necessary to put down the units. For example, if the answer is 25 billion and you put down 0.25 and show your work where you took out some of the zeroes, will you get full credit?
only a grader can answer that -- my guess is that it would depend on what the question is looking for and whether the grader is convinced that you've got the answer but for the semantics