A7FB
      +---------
077E6 | ADBFEB8A
       -A5FC1
        =====
         86A0B
        -80A47
         =====
          E4AA8
         -EB118
          =====
           5C53A
          -CF2BD
           =====
            6EF7

base: 16
letters: 0123456789ABCDEF
difficulty: hard
missing: 9