0000
      +---------
60900 | 63152311
       -60900
        =====
         63303
        -60900
         =====
          65411
         -60900
          =====
           10661
          -60900
           =====
            91A6

base: 11
letters: 0123456789A
missing: 7 8
hints: 5 < 7, A << 8
difficulty: intermediate
restrictions: no multiplication for one