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sowawa/gist:5610150

Last active December 17, 2015 12:29
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luhn check sum(ISO 7812)
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gistfile1.rb
"4242424242424242".reverse.chars.each_with_index.map{|ch, index| index.even? ? ch.to_i : (ch.to_i * 2) % 10 + (ch.to_i * 2) / 10 }.inject(:+) % 10 == 0
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sowawa commented May 20, 2013

luhn check

usage

def luhn number
  number.reverse.chars.each_with_index.map{|ch, index| index.even? ? ch.to_i : (ch.to_i * 2) % 10 + (ch.to_i * 2) / 10 }.inject(:+) % 10 == 0
end

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