Now there are wooden sticks with lengths of 1 cm, 2 cm, 3 cm, ..., 9 cm each (it is stipulated that they are not allowed to be broken). How many different methods can be used to form a square by choosing several sticks from them.
今有长度分别为1厘米、2厘米、3厘米、…、9厘米长的木棍各一根(规定不许折断)，从中选用若干根组成正方形，可有多少种不同方法．
<gadget id="calculator">8 + 1</gadget>
<output>9</output>

<result>9</result>