536B
      +---------
23827 | 4A98427A
       -23827
        =====
        680A52
       -698687
        ======
         5378A7
        -5645B3
         ======
          5A973A
         -5052A1
          ======
           5319A

base: 12
letters: 0123456789AB
difficulty: medium
restrictions: no multiplication