5A38
      +---------
74282 | 188422BB
       -74282
        =====
        7B7122
       -413782
        ======
         60482B
        -683422
         ======
          B3B2BB
         -B32622
          ======
            50BB

base: 12
letters: 0123456789AB
difficulty: medium
missing: 9