????????
      +---------
B127B | BAA3D67B
       -B127B
        =====
         1DAA6
        -CA7DC
         =====
         B05677
        -B0B057
         ======
           D6C0B
          -A5989
           =====
           ?????

base: 14
letters: 0123456789ABCD
difficulty: medium
hints: 9 << 8, 4 << 5
missing: 4