Deciphering the Numbers
Look toward the bottom of the front of the deposit slip for two sets of numbers. One set will be a routing transit number, which identifies the bank that hosts the account. The routing number is nine digits long and is bracketed by a symbol that looks a bit like a short vertical dash with two dots next to it. The other set of numbers is the account number; the number of digits in this number varies by bank.
Blank deposit slips -- the ones banks have on hand in the lobby for people coming in -- don't have account numbers printed on them. Customers must write their account numbers on the slips.