SQL & PL/SQL

I am trying to do a SELECT to get all SSN which are in the database as 9 digit numbers. What I want to do is output these 9 digit numbers as NNN-NN-NNNN instead of NNNNNNNNN

So when SSN colum reads out it would not look like this:
007830838

it would look like this instead:

007-83-0838

How would I do the SELECT statement properly?
It might go something like -- SELECT SSN from database.tablename;
only with an added proper function to convert the output.

Thanks,
-T