Know Thy Numbers

Series are very popular in fantasy and science-fiction. And of numbered series, trilogies are the most popular ones, probably because they date back to ancient times, to the festivals of ancient Greece. However, just like the word trilogy, there are others that cover series from 2 to 10 works:

Number of Works	Name (Greek)	Name (Derivative)
2	-	Duology can be used.
3	Trilogy
4	Tetralogy	Quadrilogy is occasionally used.
5	Pentalogy
6	Hexalogy
7	Heptalogy
8	Octalogy
9	Ennealogy
10	Decalogy