As far as answering questions like that on the test goes, you can usually toss out two of the answers pretty quickly and know which one is right without actually doing the math.
For example. Let's say the choices are:
A) 1645
B) 1523
C) 1611
You can exclude A and B right away because they don't fall between 1630 and 1533.
Or if they give you something like this:
A) 1545
B) 1611
C) 1510
You can look at that and notice right away that C isn't right, because it doesn't fall between the two. Next you notice that 28.22 is pretty close to 28.2, so you know that the resulting altitude should be pretty close to 1630. That makes B the right answer.
This isn't a test where you actually have to show your work. That is coming up in the Oral and practical test. Don't make it harder than it needs to be. This is just a multiple choice test. Use some of the test taking skills you learned when you were getting ready to take the SAT in highschool.
On top of that, there are only three answers to choose from. Usually one of the answers can be discounted very quickly, and the other can be discounted with a little bit of though. If you know two answers are wrong, the third must be right.