On the Subject of Chicken Nuggets

The things mathematicians do in their free time are questionable.

• You are a homeless man who recently got hired at the small restaurant down the street called McDonald’s.
• The McDonald’s corporation sell chicken nuggets in packs of six, nine, and twenty, all of which relate to the corresponding buttons in the bottom row in the previously mentioned order.
• A customer will order a certain amount of chicken nuggets as shown in black text, and you must give him his exact order.
• To add to your current nugget amount, press their corresponding buttons. Press the button on top to give your current nugget amount to the customer.
• If the customer wants an amount of chicken nuggets that is simply impossible to make, then hold the button to drown the customer and get a bonus check by your boss.
• If the customer receives too many nuggets, he dies of obesity. If he receives too little, he will starve to death. Both scenarios will result in your termination.