ABA Routing Number check digit validation

Following on from the IBAN check digit validation I decided to share some code to validate an ABA routing number. The routing number is a 9 digit number. Each digit is multiplied by a particular number (3, 7, or 1) depending on its position, the total added up and then divided by 10. The routing number is considered valid if there is no remainder. You can download the code and the test case.