'One fifth' in the Bible

Let Pharaoh take action to appoint overseers and officials over the land, and set aside one-fifth [of the produce] of the [entire] land of Egypt in the seven years of abundance.

At harvest time [when you reap the increase] you shall give one-fifth of it to Pharaoh, and four-fifths will be your own to use for seed for the field and as food for you and those of your households and for your little ones.”