Oh my friend :D There were 54 books... in the MAIN series. There were also four Megamorphs books (stories about the Animorphs that you didn't have to read to enjoy the main series but were fun), four Chronicles (spin-off books that gave background on some of the alien characters and species), and two choose your own adventure books.

There was a lot of Animorphs to enjoy! And yet I still yearned for more. Actually there were a few more books they planned to write in the Animorphs universe (including an 'encyclopedia' full of short stories) but didn't get around to, sadly.

There were times that it was so bad, it was funny, but I still yearn for a decent adaptation for the books.