6583
      +---------
62025 | 36A16658
       -35855
        =====
         A21665
        -A34525
         ======
          A6A458
         -A58325
          ======
           A2628

base: 12
letters: 0123456789AB
hints: B << 9, 1 << 7
difficulty: hard
missing: 7 B 9