XUGR
      +---------
XHLQM | QXYFGRTM
       -MXUMH
        =====
        LTWHPR
       -HQMFLR
        ======
         HRWXTT
        -HPRWPL
         ======
          HMQRQM
         -HUURXQ
          ======
           HXTRQ

base: 13
letters: FGHLMPQRTUWXY
difficulty: medium
restrictions: no multiplication