
MHB Master
#1
August 24th, 2018,
17:59
Use the UPC scheme to determine the check digit for the number $07312400508$.
here is the example from the book
ok so going with dot product with 07312400508
\begin{align*}\displaystyle
&\quad (0731 2 4 0 0 5 0 8)\cdot(3,1,3,1,3,1,3,1,3)\\
&= 0\cdot3+7\cdot1
+3\cdot3+1\cdot1
+2\cdot3+4\cdot1
+0\cdot3+0\cdot1
+5\cdot3+0\cdot1
+8\cdot3 \\
&=7+9+1+6+4+15+24\\
&=66\\
66mod10&=6
\end{align*}
so far?? but the number only has 11 digits
Last edited by karush; August 24th, 2018 at 19:57.

August 24th, 2018 17:59
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MHB Oldtimer
#2
August 25th, 2018,
03:58
Originally Posted by
karush
ok so going with dot product with 07312400508
\begin{align*}\displaystyle
&\quad (0731 2 4 0 0 5 0 8)\cdot(3,1,3,1,3,1,3,1,3)\\
&= 0\cdot3+7\cdot1
+3\cdot3+1\cdot1
+2\cdot3+4\cdot1
+0\cdot3+0\cdot1
+5\cdot3+0\cdot1
+8\cdot3 \\
&=7+9+1+6+4+15+24\\
&=66\\
66\pmod{10}&=6
\end{align*}
so far?? but the number only has 11 digits
That is correct so far. You now have to add a twelfth digit so as to make the checksum zero$\pmod{10}$.

MHB Master
#3
August 25th, 2018,
06:25
Thread Author
Originally Posted by
Opalg
That is correct so far. You now have to add a twelfth digit so as to make the checksum zero$\pmod{10}$.
What would be the 12th digit????

MHB Oldtimer
#4
August 25th, 2018,
06:34
Originally Posted by
karush
What would be the 12th digit????
What do you have to add to 66 to get a multiple of 10?