????????
      +---------
8C56D | B74D7234
       -8C56D
        =====
         3E1D2
        -4E4F0
         =====
          2AF23
         -EE6B7
          =====
           925A4
          -A20C3
           =====
           ?????

base: 16
letters: 0123456789ABCDEF
difficulty: hard