I wasn’t taught any of this in my day. You don’t have to use the clock unless you want to know the answers, presumably. I felt so smug I didn’t bother, ha ha.
The middle-aged comedian Dara O’Briain, formerly a theoretical physicist to Ph D level, completed an O-level maths exam in ten minutes and got an A* and dismissed the format as largely useless if that’s any encouragement. I think the young of today get a couple of hours for O-level maths, etc.