I think I am qualified to answer this question, because I was also a careless person in high school. Every time I take a math exam, I either read the questions or make mistakes on the sketch paper, and I lose a lot of "grievance points" every time. Therefore, I suggest that you should do the following:

1. Examine the questions carefully. Maybe the teacher emphasizes every time that many people don't care. However, it is not so easy to really see and understand the topic, especially in the high school exam under such great mental pressure. Therefore, if you want to do your homework at ordinary times, you must exercise your reading ability and examination ability.

2. Cultivate good thinking habits. The answer sheet is full but you can't find the answer, which shows that your thinking is not clear enough when you answer the question. Write a score here and a score there. When you think clearly, you will consider all the situations of this problem, from simple to difficult. You can't miss your own answer.

3. Develop good writing habits, develop a way of thinking, and have good writing habits, which will make your paper look cleaner, and the marking teacher will also give you an appropriate "punch".

Finally, I hope you can accept my suggestion and find a way that suits you. I wish you better and better grades in the future.