'One third' in the Bible

He commanded them, saying, "This [is] the thing which you must do: one third of you {who go off duty on the Sabbath}, the keepers of the guard in the house of the king,

This is the thing that you must do: one third of you priests and Levites {coming off duty on the Sabbath} [shall be] gatekeepers at the entrances

and one third at the house of the king, and one third at the Gate of the Foundation. And all the people [shall be] in the courtyards of the house of Yahweh.

{And then} in all the land," {declares} Yahweh, "{two thirds} will be cut off and perish, and one third will be left alive in it.