79525
     +---------
7023 | 09514527
      -2217
       ====
       78744
      -77659
       =====
        17215
       -11675
        =====
         15462
        -18096
         =====
          11727
         -11675
          =====
            779

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