[Mahray]

My standard for judging this is can I give it to a random, non-maths person, and have them follow the work.

Often one of the criteria you are being assessed on is communication (under various names). For a question like that, there's not much you can do, but as they become more complex you do need to show step by step what you are doing and how you are thinking about things.

Connor - In my classes, I try to show multiple methods of solving a problem and communicating, and I'll accept any method that works.

The other reason for communication, particularly in longer questions, is that you can make a mistake and still be awarded nearly full grades. If I can see a student knows what they're doing and has just written down a wrong number, or got two numbers mixed up - I'll award full marks, because they know what they're doing.

Erika - have you got any different examples? Also, talking to your teacher and asking them to show you what it should look like would be a good idea (another example - when I write an answer scheme I do it showing full working).