-- Define the function
CREATE OR REPLACE FUNCTION PowerNN (x IN NUMBER, n IN NUMBER) 
RETURN NUMBER 
IS
   result NUMBER;
BEGIN
   result := POWER(x, n);
   RETURN result;
END;
/
-- Use the function
DECLARE
   x NUMBER := &x;  -- Base
   n NUMBER := &n;  -- Exponent
   result NUMBER;
BEGIN
   result := PowerNN(x, n);
   DBMS_OUTPUT.PUT_LINE(x || ' power ' || n || ' is ' || result);
END;
/