I have ADHD not add, but I suppose I could help, first, divide yourself from getting distracted, solely focus on the test and if your mind starts to wander or get bored just do even more

the pomodoro technique really helps me, and a lot of people with adhd, with school! if you haven’t heard of it, it’s a time management technique where you (usually) work for 25 minutes, then take a 5 minute break. after you complete that pattern 4 times, you get a long break of 30 minutes. you can vary the times a bit for what works best for you, but that’s the basic pattern. this has been such a game changer for me when doing homework and studying. there’s lots of great pomodoro apps out there that make it more engaging as well. hope this helps! :)