NNN
       +---------
RFNFNH | RMNCCWRF
        -RFNFNH
         ======
          MFCNGR
         -RFNFNH
          ======
          NFWNLNF
         - RFNFNH
          =======
           WWFCMC

base: 10
letters: CFGHLMNQRW
difficulty: intermediate
restrictions: no multiplication
missing: Q