I'll admit I never heard of it, but then I'm retired and not in Scotland.
When I googled it though, a sample paper came up which is as good an indication as you can have.
As with any exam, READ THE QUESTIONS CAREFULLY. It's multiple choice answers but you should work out the arithmetic first before looking at the options. It gives a good feeling when your answer is there, and if it isn't you know you've to try that one again. I would think it will be Ok to write your workings out on the paper if you want to; I know I would.
Finally if you have spare time at the end spend it checking your answers.
Good luck.