The Hebrew Bible is divided into two 17 books and one 9 books:

17 form the historical foundation (Genesis to Esther), 1 the prophetic (Isaiah to Malachi) and 17 the foundation of experience (Job to Song of Songs). Attention: The Psalms were originally 9 books. The division can still be seen in many Bible translations today. Volume 5 begins with Chapter 2, the following volumes with Chapters 42, 73 and 90.

The two rows of 17 are each divided in parallel into 5 main books (the Torah/Isaiah to Daniel), 9 subsequent books (Joshua to 2 Chronicles/Hosea to Zephaniah), which were written before the Babylonian exile, and 3 post-exilic (Ezra to Esther/ Haggai to Malachi).

The New Testament also has 5 main books (Matthew to Acts). They represent the historical foundation. The following 9 books were written primarily for Gentile Christians (Romans to 2 Thesalonians), another set of 9 books primarily for Jewish Christians (Hebrews to Revelation) and 4 books are pastoral epistles to individuals (1 Cor. Timothy to Philemon).

This count gives a total of 70 Bible books.