'Thirty' in the Bible

Then he brought me into the outer courtyard, and behold, there were chambers and a pavement made for the courtyard all around; thirty chambers faced the pavement.

The side chambers were three stories [high], one above another, and thirty chambers in each story; and the side chambers extended to the wall which stood on their inward side all around, so that they would be attached, but not attached to the wall of the temple itself.

In the four corners of the courtyard there were enclosed courtyards, forty cubits long and thirty wide; these four in the corners were the same size.