How to formulate a multiple if/then/else statement?

I’m trying to formulate a logical function that depends on a “Choice” field.

If ChoiceType =1, then I want to display the result of Formula_1

If ChoiceType =2, then I want to display the result of Formula_2

If ChoiceType =3, then I want to display the result of Formula_3

If none of these choices are selected, I want to display “Not Assigned”

 

Here is the basic formula I’ve been trying to use:

if ChoiceType = 1 then FormulaI_1

if ChoiceType = 2 then FormulaI_2

if ChoiceType = 2 then FormulaI_3

else “Not Assigned”

end

 

I have also tried using “or” and “and” between each condition, but it isn’t working.  Can you please help?