3 ms·
It could be correct in base-11: ISBN-10 (https://en.wikipedia.org/wiki/ISBN#ISBN-10_check_digits https://en.wikipedia.org/wiki/ISBN#ISBN-10_check_digits) actual
by zinekeller 4y ago
It could be correct in base-11: ISBN-10 (https://en.wikipedia.org/wiki/ISBN#ISBN-10_check_digits https://en.wikipedia.org/wiki/ISBN#ISBN-10_check_digits) actually uses digits 0-9 and then X (rather clever use of Roman numerals, it of course means 10) due to then-limited understanding of check digits when it was first standardised (the Luhn algorithm was not invented yet).