Can you solve this McNuggets Puzzle || Computer Programming Puzzle

Verify your answer of bonus puzzle here :
http://mathsjavascript.free.fr/frobenius_9_page.html
Simply type the values as 9,12,25 and you get the result as 65.

Problem statement:
At McDonald’s you can order Chicken McNuggets in boxes of 6, 9, and 20.
for instance. If you want 32 pieces, then you can buy one box of 20 and two boxes of 6.
But if you want 16, then you won't be able to buy it with any combination.
What is the highest number of McNuggests that cannot be bouhgt with any combination of these boxes?

This Puzzle is algorithm based puzzle. It also has a very interesting mathematical solution. In this video I have explained both the methods.
Algorithmic approach is used for writting computer programs.

Видео Can you solve this McNuggets Puzzle || Computer Programming Puzzle канала LOGICALLY YOURS