How do I find the number of elements in a set that has exactly $16$ subsets and an odd number of elements?
I don't really understand.
I mean I know that the number of subsets in a set is equal to $2^n$, where $n$ is the number of elements in the set. So here if the number of subsets is $16$, I would say that the set has $4$ elements ($2^4 = 16$). But it says that the set has an odd number of elements.. and $4$ is not odd. In the book, the answer is $5$, and I don't understand how that would be.