The UKCAT is a test where to obtain the highest score (900), you need to have a score equal to or higher than the best candidate in that section who took the test in 2006 (the first year the test became available and the baseline for comparisons). This means you do not need to finish every question or necessarily get every question right to get a score of 900.
In quantitative reasoning, each question is weighted equally, meaning that a correct answer adds the same amount of score to your total. However, not all questions are equally as easy to complete as others, especially in quantitative reasoning. What I would recommend is to skip questions on economics and interest because they tend to take longer to complete. If you have time at the end, you can go back to it, but if not you will complete more questions by skipping those ones thus meaning you will probably get a higher score. What is important in the sections is that you don’t rush too much and instead focus on getting most or all of the questions you attempt correct but with reasonable pace. I remember when taking my test, I missed the last four questions and still scored 850 in the quantitative reasoning.
The other techniques you can use for the maths is the process of elimination and what some people term as “eyeballing the data”. You do not necessarily need to work out the answer definitely, but be sure that the other options are incorrect (process of elimination). This means with some graphs and other work, you can look at the graph and know what the answer is with reasonable confidence, without having to do the numbers work. This allows you more time to work on the other questions. The final tip is if you don’t know how to get the answer, generally 2-3 of the answer options are fairly clearly wrong and by eliminating those and guessing between the 2-3 plausible answers left, you have increased your odds of the answer being correct by guesswork from 1 in 5 (20%) to 1 in 2 (50%) or 1 in 3 (33%). Chances are this will boost your score.