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).




nonMcNuggets: function [lim][
    result: new 0..lim
 
    loop range.step:6 1 lim 'x [
        loop range.step:9 1 lim 'y [
            loop range.step:20 1 lim 'z 
                -> 'result -- sum @[x y z]
        ]
    ]
 
    return result
]
 
print max nonMcNuggets 100