????????
      +---------
4A07D | 24A0B4DD
       -4A07D
        =====
        32B1A4
       -309B94
        ======
         81481D
        -06A1D3
         ======
          02006D
         -08CD98
          ======
          ??????

base: 14
letters: 0123456789ABCD
difficulty: hard
missing: 5