10 DIM N(100) : rem  10 ARRAY N for Quite BASIC
20 FOR A = 0 TO 100/6
30  FOR B = 0 TO 100/9
40   FOR C = 0 TO 100/20
50    LET K = A*6+B*9+C*20
60    IF K <= 100 THEN 80
70    GOTO 90
80    LET N(K) = 1
90   NEXT C
100  NEXT B
110 NEXT A
120 FOR K = 100 TO 1 STEP -1
130  IF N(K) <> 1 THEN 160
140 NEXT K
150 STOP
160 PRINT "Maximum non-McNuggets number is: "; K
170 END