The number of books in the Old Testament varies depending on the religious tradition:

• The Protestant Old Testament contains 39 books. These are divided into the Pentateuch (first five books), Historical Books, Wisdom Books, and the Prophets

• The Catholic Old Testament includes 46 books, which is more than the Protestant version due to additional texts

• Orthodox and other traditions have even more books in their Old Testament canon

• The Hebrew Bible (Tanakh), which corresponds closely to the Old Testament, traditionally has 22 or 24 books, as some books are combined that are split in the Christian Old Testament

In summary, the most common count is 39 books in the Protestant Old Testament, but this number can be higher in Catholic and Orthodox Bibles, and lower in the Jewish Tanakh due to different arrangements and combinations of texts.