'Fifth' in the Bible

The twilight and the dawn were the fifth day.

God heard what Leah had said, so she conceived and bore a fifth son for Jacob.

Also, let Pharaoh immediately proceed to appoint supervisors over the land of Egypt, who will collect one fifth of its agricultural production during the coming seven years of abundance.

When harvest season arrives, you are to provide a fifth of the harvest to Pharaoh. The remaining four fifths are to be for your use, for seed, and to feed you, your households, and your little ones."

So Joseph crafted a statute concerning Egypt that remains valid to this day that Pharaoh should own a fifth of the produce, excluding the land belonging to the priests, which remained outside of Pharaoh's control.