NUMTOYMINTERVAL(x, interval_unit) converts the number x to an INTERVAL YEAR TO MONTH with the interval for x supplied in interval_unit. : NUMTOYMINTERVAL « Date Timestamp Functions « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. Date Timestamp Functions
3. NUMTOYMINTERVAL

You may set interval_unit to YEAR or MONTH.

SQL>
SQL> SELECT
  2    NUMTOYMINTERVAL(1.5, 'YEAR'),
  3    NUMTOYMINTERVAL(3.25, 'MONTH')
  4  FROM dual;

NUMTOYMINTERVAL(1.5,'YEAR')                                                 NUMTOYMINTERVAL(3.25,'MONTH')
--------------------------------------------------------------------------- ---------------------------------------------------------------------------
+000000001-06                                                               +000000000-03

SQL>