Indeed, you see such a code on your books these days with their isbns. It is the same code except they use only ten decimal digits, and, ten not being a prime number, they had to introduce an eleventh symbol, labeled X, which might at times arise in the parity check—indeed, about every eleventh book you have will have an X for the parity check number as the final symbol of its isbn. The dashes are merely for decorative effect and are not used in the code at all. Check it for yourself on your textbooks. Many other large organizations could use such codes to good effect, if they wanted to make
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