The publishers of Harry Potter corrected an error in one of JK Rowling's books after readers spotted a mistake, it has been revealed.
Harry Potter and the Half-Blood Prince went on sale in July 2005
The hard-back edition of Harry Potter and the Half-Blood Prince stated that Hermione Granger scooped 11 top results in her Ordinary Wizarding Level exams.
But a previous book said she had only taken 10 subjects.
A spokeswoman for Bloomsbury said the error was noticed just after the book was published last year and changed.
It was fixed for the next edition, downgrading Hermione's results from one Exceeds Expectations and 10 Outstanding grades, to nine Outstandings and one Exceeds Expectations.
Because of the popularity of Harry Potter, fresh print runs are ordered as soon as the previous batch heads for the shops in order to keep up with demand.
A Bloomsbury spokeswoman said: "It was corrected immediately."