# File lib/active_merchant/billing/check.rb, line 52 def valid_routing_number? d = routing_number.to_s.split('').map(&:to_i).select { |d| (0..9).include?(d) } case d.size when 9 then checksum = ((3 * (d[0] + d[3] + d[6])) + (7 * (d[1] + d[4] + d[7])) + (d[2] + d[5] + d[8])) % 10 case checksum when 0 then true else false end else false end end