'Thirty' in the Bible

Now the time that the sons of Israel lived in Egypt was four hundred and thirty years.

And at the end of four hundred and thirty years, to the very day, all the hosts of the Lord went out from the land of Egypt.

If the ox gores a male or female slave, the owner shall give his or her master thirty shekels of silver, and the ox shall be stoned.

The length of each curtain shall be thirty cubits, and the width of each curtain four cubits; the eleven curtains shall have the same measurements.

The length of each curtain was thirty cubits and four cubits the width of each curtain; the eleven curtains had the same measurements.