Wikipedia
The McNuggets version of the coin problem was introduced by Henri Picciotto,
who included it in his algebra textbook co-authored with Anita Wah. Picciotto
thought of the application in the 1980s while dining with his son at
McDonald's, working the problem out on a napkin. A McNugget number is
the total number of McDonald's Chicken McNuggets in any number of boxes.
In the United Kingdom, the original boxes (prior to the introduction of
the Happy Meal-sized nugget boxes) were of 6, 9, and 20 nuggets.

Task

Calculate (from 0 up to a limit of 100) the largest non-McNuggets
number (a number n which cannot be expressed with 6x + 9y + 20z = n
where x, y and z are natural numbers).




10 N=0
20 :N+1)=0
30 N=N+1
40 #=100>N*20
50 A=0
60 B=A
70 C=B
80 :C+1)=160
90 C=C+20
100 #=100>C*80
110 B=B+9
120 #=100>B*70
130 A=A+6
140 #=100>A*60
150 N=101
160 N=N-1
170 #=:N+1)
180 ?="Largest non-McNuggets number: ";
190 ?=N