CQHN
      ----------
 NHNN ) CQEFAXQA
       -XNTNQ
        =====
         QHFCX
        -TNXNC
         =====
          HHCNQ
         -QNFNX
          =====
           NXAEA
          -HNANF
           =====
            XNEN

base: 10
symbols: ACEFHNQTUX
difficulty: intermediate
missing: U