1. Some students aren't good at math.

Question

2. Any students aren't good at math.
3. No students are good at math.
4. A few students aren't good at math.
[Which one is ungrammatical? Do you use #1 more than #4? Which one is commonly used?]

5. I don't have any books.
6. I don't have some books.
7. I have no books.
[#5 means #7. What about #6? Do you use #6?]

Answer 1

#2 is not good grammar in that it doesn't make sense. "Any students"? #1 and #4 mean the same thing, and either can be used. #3 is simply not true, so no one would say it.

#6 means you have some books but not others.