WQJ
       +---------
CHCCXL | PPQGGJWQ
        -PCGPPP
         ======
          HHJLQW
         -CHCCXL
          ======
          CNGGXHQ
         -QLWJNPC
          =======
           QCJHGL

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