"tens of "or "dozens of"
If I want to describe I have 20-50 books. Is it tens of books or dozens of books? What if it refers money between 20-50 dollar, I use tens of dollar or dozens of dollar?

Question

"tens of "or "dozens of"
If I want to describe I have 20-50 books. Is it tens of books or dozens of books?  What if it refers money between 20-50 dollar, I use tens of dollar or dozens of dollar?

Answer

Either is fine.  It doesn't have to precise. Dozens sounds better to me though... but if only about 20 I probably wouldn't use either as they imply more than that.