0762
      +---------
578A5 | 21504772
       -578A5
        =====
        0A7077
       - 832A3
        ======
         048267
        -04A302
         ======
           34402
          -621A4
           =====
           020A3

base: 11
letters: 0123456789A
difficulty: intermediate
missing: 9