Created
June 1, 2011 18:43
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Convert ISBN10 to ISBN13
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| def isbn10_to_isbn13(isbn10) | |
| i = 30 | |
| s = '978' + isbn10.to_s[0..8] | |
| 4.step(12, 2) do |j| | |
| i += s[j-2, 1].to_i + (3 * s[j-1, 1].to_i) | |
| end | |
| s + ((10 - (i % 10)) % 10).to_s | |
| end |
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