SQL: Structured Query Language - Oracle 10g Database Administration Concepts and Implementation Made Simple - page 32

Output:
Round
----------
30
Example:
SELECT TRUNC(25.29,1) "Truncate"
FROM DUAL;
Output:
Truncate
----------
25.2
SELECT TRUNC(25.29,-1) "Truncate"
FROM DUAL;
Output:
Truncate
----------
20
-1 will truncate (make zero) first digit left of the decimal point of
25.29
Example:
SELECT MOD(11,4) "Modulus"
FROM DUAL;