stuck with one query in SQL Server

Question

I had a table named calci. The following was the sample data

CREATE TABLE calci
    (RN int, FREQ int, price int)
;

INSERT INTO calci
    (RN, FREQ, price)
VALUES
    (1, 1, 3),
    (2, 2, 4),
    (3, 3, 5),
    (4, 4, 6),
    (5, 5, 7),
    (6, 6, 8),
    (7, 1, 5),
    (8, 2, 6),
    (9, 3, 9),
    (10, 4, 7),
    (11, 5, 5),
    (12, 6, 1),
    (13, 1, 3)
;

I required only 3 records based on the sum of freq (1-6)

The result should be like

price
33 -----sum of first 6 records    
33 -----sum of next six records    
3  -----sum of last six record i.e last record

Answer 1

please check the following query which will solve the above problem

select sum(price) from calci  group by (rn- freq)

Answer 2

SELECT SUM(price)
FROM calci
GROUP BY (RN - 1) / 6
HAVING (RN - 1) / 6 IN (0, 1)
UNION
SELECT SUM(price)
FROM calci
WHERE (RN - 1) / 6 = (SELECT (COUNT(*) - 1) / 6 FROM calci)