'Mayest' in the Bible

Only the LORD give thee wisdom and understanding, and give thee charge concerning Israel, that thou mayest keep the law of the LORD thy God.

Now, behold, in my trouble I have prepared for the house of the LORD an hundred thousand talents of gold, and a thousand thousand talents of silver; and of brass and iron without weight; for it is in abundance: timber also and stone have I prepared; and thou mayest add thereto.