Title: Animorphs
Content:  The series consists of 54 books and includes ten companion books, eight of which fit into the series' continuity (the Animorphs Chronicles and Megamorphs books) and two that are gamebooks not fitting into the continuity (the Alternamorphs books).
Title: These Are the Voyages (book series)
Content:  Originally, These Are the Voyages was to be published as one book, but with over 2,000 pages of material, it was decided to break it into three books, one book for each season.
Title: Okko's Inn
Content:  The novel series has over 3 million volumes in print.
Title: Bloomsbury 21
Content:  The 21 books in the series are listed here:
Title: Lone Wolf (gamebooks)
Content:  The New Order Series (gamebooks 21 to 32) is intended to be 12 books long, although only the first eight books were originally released before the cancellation of the series in 1998. It took 18 years before the next book in this subseries got published. It features a new protagonist, a Grand Master in the Second Order of the Kai and a student of Lone Wolf, who is now Supreme Master. This series allows the player to 'customize' his character by allowing the choice of an individual name (originally, the name was speculated to be Falco Nero, or Black Hawk). Much 
Title: The Stuff of Legend
Content: Book 1: The Dark (collects Volume 1: The Dark, Issues 1 and 2, 128 pages, Villard Books, April 2010, ISBN: 0-345-52100-5) ; Book 2: The Jungle (collects Volume 2: The Jungle, Issues 1 through 4, 144 pages, Th3rd World Studios, April 2011) ; Book 3: A Jester's Tale  (collects Volume 3: A Jester's Tale, Issues 1 through 4, 124 pages, Th3rd World Studios, March 2012, ISBN: 0-9832161-2-6) ; Book 4: The Toy Collector  (collects Volume 4: The Toy Collector, Issues 1 through 5, 124 pages, Th3rd World Studios, August 2013) ; The Stuff of Legend: Omnibus One [Hardcover] (collects Volume 1: The Dark and Volume 2: The Jungle, 260 pages, Th3rd World Studios, July 2012, ISBN: 0-9832161-9-3) ; The Stuff of Legend: Omnibus Two [Hardcover] (collects Volume 3: A Jester's Tale and Volume 4: The Toy Collector, 270 pages, Th3rd World Studios, February 2014, ISBN: 0-9895744-9-0) The comics collected into trade paperbacks: 
Title: The Idhún's Memories
Content:  At first, there were six books: Búsqueda (search), Revelación (revelation), Despertar (awakening), Predestinación (predestination), Convulsión (convulsion) and Génesis (genesis). However, the author and the publisher agreed to merge every two titles into one book, and give the three of them a similar length (28 chapters, a preface and an epilogue). Those are the three books we know today. SM has now relaunched the series, divided into the six initial books. The series has also been adapted into comic books.
Title: The Complete Peanuts
Content:  Peanuts Every Sunday is a series featuring the Peanuts Sunday strips in full color. These books, unlike the Complete Peanuts series, are scheduled to be released one every year, in 10 volumes covering half a decade each (except the first book, 1952–55). Slip-cased sets of two are also available. Box sets Both the complete series and the Sunday collections are being published in hardback and paperback form, with different covers and supplemental artwork.
Title: Alfred Escher
Content: The series is to be continued (to a total of six volumes). The series is to be continued (to a total of six volumes). The series is to be continued (to a total of six volumes). The series is to be continued (to a total of six volumes). The series is to be continued (to a total of six volumes). The series is to be continued (to a total of six volumes). 
Title: 33⅓
Content:  , 159 books have been published in the main series.

Question: how many books are in the one piece series?
Answer: 83.
more than 80.