SQL & PL/SQL :: Function To Sum Five Numbers

I am creating a function to sum five numbers (less 1). Is it possible to have an array of numbers in an SQL function, and how would this be implemented?

Here is the screenshot of my output (I cannot embed links until 5 posts!): flic.kr/p/eaSHBP

CREATE OR REPLACE FUNCTION sumfivenumbers ( n1 NUMBER, n2 NUMBER, n3 NUMBER, n4 NUMBER, n5 NUMBER)
RETURN NUMBER
IS
Sumnums NUMBER;
BEGIN
SELECT SUM(n1+n2+n3+n4+n5-1) INTO Sumnums FROM DUAL;
DBMS_OUTPUT.PUT_LINE(Sumnums);
RETURN 1;
END sumfivenumbers;
/
SELECT sumfivenumbers(5,5,5,5,5) AS "Five Numbers less 1" FROM DUAL;