RRG
       +---------
FGRWLX | TXXTTNFR
        -TNGJWW
         ======
          TWGXRF
         -TNGJWW
          ======
           JLMTTR
          -JMXXJN
           ======
            TFWMR

base: 10
letters: FGJLMNRTWX
difficulty: medium
restrictions: no multiplication