create table testme
(
       event_date DATE,
       team_count NUMBER,
       interview_count NUMBER,
       duration DATE
);



insert into testme (event_date, team_count, interview_count, duration) 
       VALUES ('01-jan-1900 08:00:00', 2, 3, '01-jan-1900 02:30:00');




select extract(hour FROM
        to_timestamp(to_char(to_date(
         (
          (e.duration * e.team_count * e.summonscount) + e.event_date),
           'dd-mon-yyyy HH24:MI:SS'),
           'dd-mon-yyyy HH24:MI:SS')))
  from testme;

SELECT (duration   - Trunc(duration))   * 24,  
       (event_date - Trunc(event_date)) * 24 
  FROM testme 

SQL> select event_date +
  2         (team_count * interview_count * to_number(to_char(duration,'SSSSS')))
  3         / 86400
  4  from testme
  5  /
EVENT_DATE+(TEAM_COU
--------------------
01-jan-1900 23:00:00

SQL> select to_number(to_char(new_date, 'HH24')) new_date
  2  FROM (select event_date 
  3               + (team_count * interview_count * (duration - trunc(duration))) AS new_date
  4        from testme);

  NEW_DATE
----------
        23

SQL>