SQL> SELECT INTERVAL'20' DAY -
INTERVAL'240' HOUR FROM dual;
INTERVAL'20'DAY-INTERVAL'240'HOUR
--------------------------------------------------------------
+000000010 00:00:00.000000000
SQL> SELECT EXTRACT (DAY FROM
(INTERVAL'20' DAY - INTERVAL'240' HOUR)) FROM dual;
EXTRACT(DAYFROM(INTERVAL'20'DAY-INTERVAL'240'HOUR))
---------------------------------------------------
10