First of all, mentality, whether it is doing problems or taking exams, is very important. You can help yourself invisibly by adjusting your mentality.

For example, I can do it, I can do it seriously, and so on.

Then practice, you can do some quick calculation exercises of oral calculation, practice every day, just stick to it, and remember the main points when doing the questions, which is also obtained from constant practice.

I hope it helps your children.