Do you happen to know if they give half marks, I often see that the working is worth 1 mark, and the answer, the other mark, so if we made a silly mistake, would we just lose it all?
I've spent the last semester marking maths assignments, and will be one of the exam markers this semester. There are generally no half marks given on maths assignments/exams. Usually if the question is slightly involved, there'll be mark for working and a mark for the answer. If you apply the right method but do it wrong (e.g. arithmetic or algebra mistake) you'll get the working mark but not the answer mark. If you write down the right answer with no working, you'll get the answer mark but not the working mark.
More difficult problems with several steps can have a lot of marks associated with them, with a few different acceptable ways to get to the right answer. Exam questions are ideally designed so that if you mess up one step of the problem, you still have a chance to get some marks if you do the next step right.
Assignments are marked quickly (think 2 or 3 minutes marking effort per assignment) and tutors are usually pretty quick to take off marks if the solution doesn't look like what they expect. Exams get given a lot more marking time, but students also screw things up a lot worse (it's really hard to solve maths problems under time pressure with no resources to consult if you're stuck!). Unusually hard exams will get scaled up.