'Seventh' in the Bible

On the seventh day, when the king’s heart was joyful with wine (in high spirits), he commanded Mehuman, Biztha, Harbona, Bigtha, Abagtha, Zethar, and Carkas, the seven eunuchs who served in the presence of King Ahasuerus [as his attendants],

So Esther was taken to King Ahasuerus, to his royal palace in the tenth month, that is, the month of Tebeth (Dec-Jan), in the seventh year of his reign.