WCHY
      +---------
YUGFM | MHMYWUGF
       -YUGFM
        =====
        WNLUFU
       -WWWGUN
        ======
         CYWHLG
        -CCNRUY
         ======
          NLYLHF
         -NNFLUR
          ======
           FWUNM

base: 11
letters: CFGHLMNRUWY
difficulty: medium
restrictions: no multiplication