Wiktionary
routing number
n. (context US English) An eight or nine digit number used by a banking institution to designate a certain geographic area used to direct and sort inquiries and transactions to the correct district, usually shown at the bottom left of a check
Usage examples of "routing number".
There was nothing on the outside but my house number and postal code, no return address, only a handwritten routing number in the left corner.
After all, there had to be some section she'd forgotten to initial, some signature block she'd forgotten to check, or-all else failing-some arcane routing number she'd somehow managed to delete from the header.
Then I gave them the routing number for the $80,000, their cash offer and apparently the going rate for people transformed into silhouettes to sell things.