Two important numbers are printed on the bottom of each check that you use in conjunction with a Chase account. One is the account number, which tells the agency that cashes the check which account to take money out of. The other is the routing number, which tells the agency that cashes the check which financial institution (in this case, Chase) holds the account.
Hold one of your Chase checks in your hand. Make sure the front is facing you.
Examine the lower-left corner on the front of your Chase check. You will see two distinct sets of numbers.
Look at the first nine digits (which will have a bracket on each side) in the lower-left corner of the check. These nine digits are your routing number.