Do more questions and think more. The common method of digital reasoning is "trial and error", that is, substitute the questions one by one according to the rules you know, but this method is suitable for beginners. After training the digital sensitivity to a certain degree, we should judge the basic types according to the laws of numbers.
As for mathematical operations, generally speaking, the test questions are not very difficult. Just because the civil service examination time is tight, I think I won't do it. For this part of the questions, you need to remember the commonly used formulas of various questions. Some types of problems can be solved directly by formulas, such as the principle of inclusion and exclusion. And when preparing for the exam, I suggest that when you analyze the meaning of the question, you should fully tap the relevant data that can be obtained under known conditions, not simply answering a question, but training your divergent thinking.
In short, you should firmly believe that the exercises in mathematics can be improved through training, and it is important to persist. You must do more exercises, be quantitative and regular, so as to ensure your sensitivity to mathematics.
I hope it helps you.