touchback - (American football) a play in which the opposing team has kicked the football into your end zone.
From Wikipedia, the free encyclopedia. A check digit is a form of redundancy check used for error detection on identification numbers, such as bank account numbers, which are used in an application where they will at least sometimes be input manually. It is analogous to a binary parity bit used to check for errors in computer-generated data.
Dissecting Check Numbers. Look at the lower left-hand part of a check and you'll see a long string of digits. The checking account number is embedded in this string. Starting from the left, the first nine digits are the bank's routing number. Routing numbers are assigned by the American Bankers Association and identify the bank that holds your checking account. After the routing number is a non-numeric symbol and then another group of four to 13 digits.