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) solids, and a standard torus can be sliced into 13 pieces with just 3 plane cuts. There are also 13 different ways for the three fastest horses in a horse race to finish, allowing for ties, a fact that can be expressed mathematically by 13 being the third ordered Bell number. In Germany, according to an old tradition, 13 ("dreizehn") -as the first compound number- was the first number written in digits; the numbers 0 ("null") through 12 ("zwölf") were spelt out. The "Duden" (the German standard dictionary) now calls this tradition (which was actually never written down as an