However it is important to note that some financial institutions have different routing numbers for electronic and paper transactions.
Routing numbers can often be found on online banking sites of the financial institution.
In some cases you would need to login into online banking to find correct routing number.
If you are still not sure which routing number to use contact your bank/credit union directly.
You can call phone number listed on your debit card or use one of the methods listed on contact page of online banking.
Below are links to pages listing routing number for some of the largest financial institutions:
Bank of America