CBB
      +--------
C9BA6 | 38E8E5C
       -E032C
        =====
        652AD5
       -6BC7EB
        ======
         65126C
        -6BC7EB
         ======
          694B9

base: 15
letters: 0123456789ABCDE
difficulty: hard
hints: 0 << 8, 1 << A
missing: 4