97% of writers never end a novel. The reason is here. Max said that in order to be on the Wall Street Journal's bestseller list, the book needs to sell at least 3,000 to 5,000 copies. As for Amazon, according to a study by Publishers Weekly, it is estimated that about 1,100 books need to be sold every day to discover the site. according to book writing service you can take help from Britain book writing. J.K. Harry Potter book-by-book rolling payment sale is not a matter of public records. However, if she earned 15% of the industry standard for each book, based on the series' total revenue of about 7.7 billion U.S. dollars, she could have earned about 1.15 billion U.S. dollars. A new paperback book is priced at $7, and the rolling cost is about $1. The creator of Harry Potter was in a welfare state when she wrote the first Harry Potter book, and she used most of her wealth for real estate, taxation and charity in the U.K.