How many books did the Greek cannon add to canon?

The term "Greek cannon" is a bit ambiguous. It's likely you're referring to the Greek Orthodox Church's canon of Scripture, which is distinct from the Roman Catholic Church's canon.

* The Greek Orthodox Church's canon includes 78 books, whereas the Roman Catholic Church's canon includes 73 books. This difference is because the Greek Orthodox Church includes seven additional books, known as Deuterocanonical books:

* Tobit

* Judith

* Wisdom

* Sirach (Ecclesiasticus)

* Baruch

* 1 Maccabees

* 2 Maccabees

Therefore, the Greek Orthodox Church's canon added 7 books to the "canonical" set of books that the Roman Catholic Church already acknowledged.