TXG
       +---------
AFYYMG | CFAYMAGX
        -AFYYMG
         ======
          QFQQYG
         -YTFFYX
          ======
          XCCCLCX
         -XTCGYTG
          =======
           XQYAXG

base: 10
letters: ACFGLMQTXY
difficulty: easy
restrictions: no multiplication