Check if entered value is in a list of values

[Former Community Member]

I need to determine rate billed based on zip code and a couple other factors.  I'm trying to determine the best route.  Each group of zip codes has around 100 possibilities.  For example 97003 in Group A would bill at $4 and 97002 in Group B would be $5. 

I really just need help with returning a value for the Groups, the other validations I have figured out but am running into difficulty with the script for that many options to check.  Hope that all makes some sense.

For Example

Group A -

97003,97004, 97005 ....

Group B

97002,97011,97016 ...

Any suggestions would be greatly appreciated.