Method isbn13CheckDigit

src/main/java/com/github/javafaker/Code.java:130–140

(CharSequence t)

    }

    private final int isbn13CheckDigit(CharSequence t) {
        String value = stripIsbnSeparator(t);
        int sum = 0;
        int multiplier = 0;
        for (int i = 0; i < value.length(); i++) {
            multiplier = i % 2 == 0 ? 1 : 3;
            sum += multiplier * toInt(value.subSequence(i, i + 1).toString());
        }

        return (10 - sum % 10) % 10;
    }

    private final String stripIsbnSeparator(CharSequence t) {
        return t.toString().replaceAll("-","");