ECC edits

src/Advanced/Error-Correcting Codes/parts/00 detection.tex

@@ -19,7 +19,7 @@ Only one of the following ISBNs is valid. Which one is it?
 
 \begin{itemize}
 	\item \texttt{0-134-54896-2}
-	\item \texttt{0-895-77258-2}
+	\item \texttt{0-895-77258-2} % oliver twist
 \end{itemize}
 
 \begin{solution}
@@ -67,18 +67,19 @@ This is called a \textit{transposition error}.
 \vfill
 \pagebreak
 
-\problem{}
+\definition{}
 ISBN-13 error checking is slightly different. Given a partial ISBN-13 $n_1 n_2 n_3 ... n_{12}$, the final digit is given by
 
 $$
  n_{13} = \Biggr[ \sum_{i=1}^{12} n_i \times (2 + (-1)^i) \Biggl] \text{ mod } 10
 $$
 
+\problem{}
 What is the last digit of the following ISBN-13? \par
-\texttt{978-0-380-97726-?}
+\texttt{978-030-7292-06*} % foundation
 
 \begin{solution}
-	The final digit is 0.
+	The final digit is 3.
 \end{solution}
 
 \vfill
@@ -127,7 +128,7 @@ Take a valid ISBN-13 and swap two adjacent digits. When will the result be a val
 \vfill
 
 \problem{}<isbn-nocorrect>
-\texttt{978-0-08-2066-46-6} was a valid ISBN until I changed a single digit. \par
+\texttt{978-008-2066-466} was a valid ISBN until I changed a single digit. \par
 Can you find the digit I changed? Can you recover the original ISBN?
 
 \begin{solution}