<image>Arrange matches to form squares as shown in the diagram:

(1) To form 1 square, you need ____ matchsticks;
(2) To form 2 squares, you need ____ matchsticks, to form 3 squares, you need ____ matchsticks;
(3) To form 10 such squares, you need ____ matchsticks;
(4) If n represents the number of squares formed, then to form n squares, you need ____ matchsticks.