1. Universality of knowledge points: The mathematics part of the senior high school entrance examination usually covers all knowledge points in primary school, including four operations, fractions, decimals, geometric figures, areas and volumes. Candidates need to master these knowledge points comprehensively.

2. Variety of questions: The mathematics part of the senior high school entrance examination usually involves multiple-choice questions, fill-in-the-blank questions, analytical questions and other questions. Candidates need to be familiar with the problem-solving methods and skills of various questions.

3. Flexibility of problem-solving ideas: The mathematics part of the junior high school entrance examination of famous schools usually designs some complicated questions, requiring candidates to flexibly use what they have learned to solve problems. Candidates need to cultivate their thinking ability and problem-solving ability.

4. The pressure of time management: The math part of the senior high school entrance examination is usually short, and candidates need to complete a large number of questions in a limited time. Therefore, candidates need to have good time management skills and reasonably arrange the order of answering questions and time allocation.

5. Difficulty of application questions: The mathematics part of the senior high school entrance examination usually designs some application questions related to real life, requiring candidates to apply what they have learned to practical problems. This puts forward higher requirements for candidates' understanding ability and application ability.

To sum up, the difficulties in the mathematics part of the senior high school entrance examination mainly include the universality of knowledge points, the diversity of questions, the flexibility of problem-solving ideas, the pressure of time management and the difficulty of application problems. Candidates need to master all the knowledge points, be familiar with the problem-solving methods and skills of various questions, cultivate their thinking ability and problem-solving ability, and have good time management ability.