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# File 'lib/chem/utils/cas.rb', line 4
def is_valid_casrn?
ary = self.split("-")
return false if not ary.length == 3
first_digits = ary[0].scan(/\d/)
return false if not first_digits.length == ary[0].length
second_digits = ary[1].scan(/\d/)
return false if not second_digits.length == ary[1].length
return false if not second_digits.length == 2
return false if not ary[2].length == 1
return false if /\d/.match(ary[2]).nil?
third_digits = ary[2].to_i
total = 0
(second_digits.reverse + first_digits.reverse).each_with_index do |digit, idx|
total += digit.to_i * (idx + 1)
end
return false if not (total % 10) == third_digits
true
end
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