自动计算 ISBN-13 的校验码

Question

这是一个简单的例子。如果我有 ISBN-13 号码的前 12 位数字。

\documentclass[12pt]{report} \parskip=12pt

\def\ISBNnumber{978-618-5645-08}

\pagestyle{empty}

\begin{document}
            
If I have a 12-digit ISBN-13 number.
            
\ISBNnumber
            
For this ISBN number check number is 3.
            
Is there a way to automatically calculate this number and 
add it at the end so that I have a complete ISBN number 
with all 13 digits, such as this number below.
            
978-618-5645-08-3
 
\end{document}

如何创建一个新命令来计算校验码，并将其添加到末尾，以便我们获得完整的 ISBN-13。如果有人知道这个问题的答案，请帮忙并提供一个例子。

Answer 1

这是数字的简单加权和

https://isbn-information.com/check-digit-for-the-13-digit-isbn.html

\documentclass{article}

\newcount\isbncheck
\def\zz#1{#1-\zzz#1}

\def\zzz#1#2#3{\isbncheck=\numexpr#1+3*#2+#3\relax\zzzb}
\def\zzzb#1#2#3#4#5#6#7#8#9{\advance\isbncheck\numexpr3*(#1+#3+#5+#7+#9)+#2+#4+#6+#8\relax\zzzc}
\def\zzzc{%
\isbncheck=\numexpr10-\isbncheck+10*(\isbncheck/10)\relax
\ifnum\isbncheck>9 \advance\isbncheck-10\relax\fi
\the\isbncheck
}
\begin{document}
        
If I have a 12-digit ISBN-13 number.
        

        
For this ISBN number check number is 3.
        
Is there a way to automatically calculate this number and 
add it at the end so that I have a complete ISBN number 
with all 13 digits, such as this number below.
 
\zz{978186197271}
      
978-618-5645-08-3

\zz{978618564508}

\end{document}