'Eighty' in the Bible

Now Barzillai was very old, being eighty years old; and he had sustained the king while he stayed at Mahanaim, for he was a very great man.

I am now eighty years old. Can I distinguish between good and bad? Or can your servant taste what I eat or what I drink? Or can I hear anymore the voice of singing men and women? Why then should your servant be an added burden to my lord the king?