How many books are there in the Old Testament?

Answer 1

There are 39 books in the Protestant Old Testament from Genesis to Malachi. If there are more than that in your Bible, it is because it is a Catholic version (46), an Orthodox version, or includes the Apocrypha in the number. That is because the Septuagent was used as the source material. It contains more books than the Masoretic text and was thus not accepted as authentic by mainstream rabbinic Judaism. After the Protestant Reformation, many Protestant Bibles began to exclude the extra books which were not accepted by the Jewish community. However, some Christan Bibles include the disputed books in their own section called the Apocrypha.

The Jewish Bible (from which the Old Testament is derived) only has 24 books, since the Christian Bibles split a number of the books into separate books.
39 42 if you count right