An International Standard Book Number (ISBN) Is Used to Identify

Multiple Choice

An International Standard Book Number (ISBN) is used to identify books. The ISBN number for some book is 0-534-36890-5. The first digit, 0, indicates the book is published in an English-speaking country. The next three digits, 534, identify the publisher (Brooks/Cole) and the next five digits identify the particular book. The last digit is a check digit, which is used as follows. Multiply the first digit by 10, the next digit by 9, and so on: ​
10(0) + 9(5) + 8(3) + 7(4) + 6(3) + 5(6) + 4(8) + 3(9) + 2(0) + 1(5) = 209
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This number is congruent to 0, (mod 11) . This is not by chance. The check digit, 5, is chosen so that this sum is 0, (mod 11) . In other words, the check digit x for the book with ISBN number 0-534-34015-x is found by considering:
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10(0) + 9(5) + 8(3) + 7(4) + 6(3) + 5(4) + 4(0) + 3(1) + 2(5) = 148 ≡ 5
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This means that for check digit x, 5 + x ≡ 0, (mod 11) . The one-digit solution to this equation is x = 6, so the check digit is 6. What is the check digit for the book with ISBN 0-8028-1430-x?
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