9810
      +---------
42CBA | 601A018E
       -42CBA
        =====
        155491
       -10D7E4
        ======
         D08AA8
        -DDE840
         ======
          CBD25E
         -CEED92
          ======
           84404

base: 15
letters: 0123456789ABCDE
difficulty: hard
missing: 3