The ABA routing number can be found in the top header and footer of the FSB website, and on the bottom of the log in screen within the FSB mobile app. To find it elsewhere, look at the bottom left corner of your checks. If you have a Personal account the first sequence of numbers, usually a nine-digit number, is your ABA (American Bankers Association) routing number. If you have a Business account the ABA number will follow the six-digit check number at the bottom of your checks. The ABA number is also known as a Routing and Transit Number, RTN, or bank number. It was established by the American Bankers Association to identify the accountholder’s bank when processing checks or depositing money to an account.