Whose name was Belteshazzar. — A parenthetic clause, introduced to remind the reader that by this name only Daniel was known to the king. (Comp. Daniel 4:8.)
Art thou able. — The king does not pretend to be ignorant of the person of Daniel. He had, in fact, only recently (Daniel 1:19-20) examined him in “matters of wisdom and understanding.” What surprises him is, that after the wise and experienced had failed to tell him his dream, one so young and a mere novice should succeed.