I have a custom field, Field A. This field should be populated with one of 3 values based on the combination of 3 other fields Field 1, Field 2 and Field 3. 

There are 44 different possible combinations of Fields 1, 2 and 3 so making Field A a formula field is not possible due to character limits. 

I have tried to make a concatenation formula field of fields 1, 2 and 3 however still can have 44 possible concatenations and do not know of a good way to use this field to populate Field A. 

Can anyone suggest what I might do here? 

I have a custom field, Field A. This field should be populated with one of 3 values based on the combination of 3 other fields Field 1, Field 2 and Field 3. 

There are 44 different possible combinations of Fields 1, 2 and 3 so making Field A a formula field is not possible due to character limits. 

I have tried to make a concatenation formula field of fields 1, 2 and 3 however still can have 44 possible concatenations and do not know of a good way to use this field to populate Field A. 

Can anyone suggest what I might do here?