All checks contain several sets of numbers: the check number, the account number, and the routing number. The routing number is unique to each bank, and it identifies the institution from which the check originated; the account number specifies the account from which the funds will be drawn; the check number indicates how many checks have been written from that account.
Reading a Routing Number on a Check
Turn the check right side up.
Locate the long strings of numbers at the bottom of the check.
Find the set of numbers set off by colons and vertical dashes.
The numbers inside these marks (usually about eight or nine numbers) make up the routing number for the financial institution that holds the account from which the money will be drawn.
Do not confuse the account number with the routing number; the account number is often longer and appears after the routing number.