'Seventh' in the Bible

Say to all the people of the land and to the priests, When you went without food and gave yourselves to grief in the fifth and the seventh months for these seventy years, did you ever do it because of me?

This is what the Lord of armies has said: The times of going without food in the fourth month and in the fifth and the seventh and the tenth months, will be for the people of Judah times of joy and happy meetings; so be lovers of good faith and of peace.