I know that the language of encodings of DFAs such that the language accepted by the DFA is infinite is decidable.
I also that if a DFA has a finite language with size greater than 50, all words must be finite so I can iterate through the set of all words over the alphabet in lenlex order, using that a whether a particular word is accepted by a DFA is decidable, and reject after the 51st word.
What I cannot work out is whether for a DFA with a language of size $ \le 50$, it is Turing Decidable whether that language has size $\le 50$.
I initially thought it was decidable, because other seemingly similar questions about languages of DFAs seem to be decidable, but after looking through theorems, tutorial questions and googling and finding nothing, I'm not sure.