worksheet4

# worksheet4 - is the last digit, obtained as follows:...

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MA 1002 Worksheet 4 Due Date: October 7, 2009 Print Name: Signature: ID #: Instructor/Section: Instructions: Explain each step using the conventions from class. Please mark solutions clearly. You will not receive full credit for a correct answer without explanation. 1. (50 points) Find out whether the numbers of the paper bills/money in your country have a check-digit scheme. If not, ±nd some other object that has a check digit scheme. Describe how it works and give an example. How useful do you think these schemes are? 2. (50 points) The check digit on the second number on the bottom of a travelers cheque
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Unformatted text preview: is the last digit, obtained as follows: Compute the sum of all other digits, then divide by 9 and take the remainder. Subtract it from 9. The result is the check digit. Is this check genuine? Verify that this check digit scheme can be used to recognize substitution of any single digit by another. Show that inversions (e.g 35 rather than 53) can not be recognized. 3. (extra) Find out how the check-digit scheme of the ISBN-code for books works. Verify that it can detect inversions. Is 0-273-00218-9 a valid ISBN-number? Why (not)?...
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## This note was uploaded on 12/09/2009 for the course MA 1002 taught by Professor N/a during the Spring '09 term at NYU Poly.

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