If you want a value dependent on the result of a comparison you use the formula "Case".
Example:
##CASE("Departmentcode", 'East', 1, 'Vest', 2, 'North', 3, 99)
With the above:
If the "Department code" has the value "Vest" it will return the result "2".
If the "Department code" has no value it will return the result "99".