????????
      +---------
88C98 | 4575475B
       -4C564
        =====
         48937
        -A4A1A
         =====
          7AC95
         -5B725
          =====
           A953B
          -A4A1A
           =====
           ?????

base: 13
letters: 0123456789ABC
difficulty: medium
missing: 0