You can also create a 'view' for the numbered table.
e.g.
create or replace view StringContacts
(name, state, age)
as
select name, state, to_char(age)
from Contacts
When you pull in the StringContacts view to the report (instead of the Contacts table), you can now link 'age' to the other string.
Not the best example, but hopefully it gets you started.