How to keep a formula from going below 0 (Keep it as 0 or higher)

Hello,

I have a currency formula field that is subtracting a number of costs from a commission owed to a sales rep. The number tends to come up negative from time to time.

I would like 1 of 2 options to support our math:

1) Set up the currency formula field so it cannot be a number below 0.

2) Create an additional field that will reflect the number shown in the currency formula field if it's above 0, and if it's less than 0 or a negative number, it will keep itself at 0

In regards to option 2, I've attempted to use rules for that to occur but once the 'Project Cost' is created with the related information from another table, it will not 'fire a change' if it changes after it's been created.

Thank You so much for your support.

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Anthony Wong
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