Section 4.5 99 (b) Here is a valid number: ~-1 g498-66132-9. Changing the 3 and 2 in positions one and three to 8 and 7 respectively produces the number §.-1 Z 498-66132-9 which is also valid. 13. (a) The test will not identify the digit that is wrong: An error of the same magnitude in two even or two odd digits will yield the same 3a + b. For example, if a universal product number begins 1234, either incorrect number 3234 or 1254 will yield the same 3a + b. (b) The test will not even identify whether the error is in an odd position or in an even position since, for example, a difference of 1 in an odd position will yield the same 3a + b as a difference of 3 in an even position. For example, if a universal product number begins 1234, the number 3a + b is the same for the incorrect numbers 2234 and 1534. 14. (a) [BB] 1-23586-98732-6; (b) [BB] ] 1-23006-98732-6. 15. Suppose that al-a2a3a4a5a6-a7aSa9alOall-X is a valid universal product code. Thus, A = 3(al + a3 + a5 + a7 + ag + all) + (a2
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This note was uploaded on 11/08/2010 for the course MATH discrete m taught by Professor Any during the Summer '10 term at FSU.