Code Snippet: Validate Routing Numbers in Python
The following code snippet can be used for validating the checksum on a ABA routing number.
def valid_routing_number(routing_number: str) -> bool:
if len(routing_number) != 9:
return False
if not routing_number.isnumeric():
return False
checksum = (3 * (int(routing_number[0]) + int(routing_number[3]) + int(routing_number[6]))) + \
(7 * (int(routing_number[1]) + int(routing_number[4]) + int(routing_number[7]))) + \
(1 * (int(routing_number[2]) + int(routing_number[5]) + int(routing_number[8])))
return (checksum % 10) == 0