International Standard Book Number in 1965, has – 340 indicating the publisher, 01381 their serial number, and 8 being the check digit. This can be converted to ; the check digit does not need to be re-calculated. Since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with "Bookland" European Article Number EAN-13s. An ISBN is assigned to each edition and variation (except reprintings) of a book. For example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January
13 (number) the number 13 has a specifically recognized phobia, Triskaidekaphobia, a word coined in 1911. The superstitious sufferers of triskaidekaphobia try to avoid bad luck by keeping away from anything numbered or labelled thirteen. As a result, companies and manufacturers use another way of numbering or labelling to avoid the number, with hotels and tall buildings being conspicuous examples (thirteenth floor). It is also considered unlucky to have thirteen guests at a table. Friday the 13th has been considered an unlucky day. There are a number of theories as to why the number thirteen became associated with bad luck, but none