The routing number identifies the bank instead of your actual account. If you and your coworker both hold accounts at the same bank, your routing numbers will be the same, even though your account numbers will be different. Small banks generally have only one routing number, while large multinational banks can have several different routing numbers. In the latter case, your routing number may be determined by the state where you hold the account.
The account number works in conjunction with the routing number. While the routing number identifies the name of the financial institution, the account number identifies your individual account. Because the account number is specific to you, it is important to protect it carefully. Anyone can find the routing number simply by contacting the bank and asking, but the bank will not divulge account numbers to anyone other than the rightful owner.
If you need to set up a new direct deposit for your paycheck or other payment, you need to supply both the routing number and the account number. These two pieces of information work together to definitively identify your account and ensure that your money ends up in the right place. Always double-check both the account number and routing number when setting up a new direct deposit or changing an existing one.
The best place to find both your routing number and your account number is in your checkbook. The checks in your checkbook contain both the routing and the account number. The routing number is typically located on the left hand side of the check at the bottom, while the account number is generally located in the middle of the check.