QQHH
      +---------
QCGQT | GMGTHCQM
       -CMCMQ
        =====
        TXXMTC
       - CMCMQ
        ======
         TQCMHQ
        -TTHMGH
         ======
          TTGHGM
         -TTHMGH
          ======
            QGXT

base: 7
letters: CGHMQTX
difficulty: easy
restrictions: no multiplication