'Thirty' in the Bible

Someone asked me, "What do you see?" I replied, "I see a flying scroll thirty feet long and fifteen feet wide."

Then I said to them, "If it seems good to you, pay me my wages, but if not, forget it." So they weighed out my payment -- thirty pieces of silver.

The Lord then said to me, "Throw to the potter that exorbitant sum at which they valued me!" So I took the thirty pieces of silver and threw them to the potter at the temple of the Lord.