To someone explaining calculus

1. I haven’t the foggiest/slightest/vaguest idea of what you’re talking about.
2. I can’t make heads or tails of it.
3. I don’t understand.
4. Whatever do you mean?
5. You’ve got me stumped.
6. I don’t know what to make of it.
7. It doesn’t make any sense.
8. How could that possibly be?
9. It’s Greek to me.

To someone explaining calculus