Currently the barcodes on a book 's back cover (or inside a mass - market paperback book 's front cover) are EAN - 13; they may have a separate barcode encoding five digits called an EAN - 5 for the currency and the recommended retail price. For 10 digit ISBNs, the number "978 '', the Bookland "country code '', is prefixed to the ISBN in the barcode data, and the check digit is recalculated according to the EAN13 formula (modulo 10, 1x and 3x weighting on alternate digits).
where does the isbn number go on a book
on a book 's back cover inside a mass - market paperback book 's front cover