8139
        +-----------
0136728 | 9246370619
         -0136728
          =======
          67628716
         -68942121
          ========
           15886591
          -59529623
           ========
            19218339
           -15392929
            ========
             1672432

base: 10
letters: 0123456789
difficulty: intermediate
restrictions: no multiplication