## mark a section (Learn more)

def valid_NIP?(nip) return false if nip.size != 10 weights = [6, 5, 7, 2, 3, 4, 5, 6, 7] nip = nip.split(//).map {|d| d.to_i } checksum = 0 weights.each_with_index {|w, i| checksum += w * nip[i] } return checksum % 11 % 10 == nip.last end

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