You should also practice more application problems. The difficulty of primary school mathematics lies in the mastery of applied problems. Mathematics is a subject that needs a lot of practice, at any time.
In addition, it depends on the theoretical formula of the textbook, and must not be discounted. The examples and exercises in the book are the most basic content and must be mastered. Don't ignore the past just because it is simple.
For careful questions, children should first check themselves after finishing their homework, and in the process of finding their own loopholes, they can gradually reduce carelessness.