Personal checks have a magnetic ink character recognition line (MICR) across the bottom...

Personal checks have a magnetic ink character recognition line (MICR) across the bottom of the check. This line includes the routing number, the account number, and the number of the check. The first nine digits across the bottom of a check make up the routing number. Of those nine digits, the first four represent the Federal Reserve routing number, the second four identify the institution, and the ninth is the check digit. The check digit of the routing number is the last digit in the following weighted sum:

Determine the check digit for each of the following routing numbers where the first eight digits have been given.

a. 06311482

b. 12200048