Now there are line segments with lengths of 1, 2, 3, 4, 5, 6, 7, 8, and 9 centimeters. In how many different ways can several strips be chosen to form a square?
今有长度是1，2，3，4，5，6，7，8，9厘米长的线段各一条．可以用多少种不同的方法，从中选用若干条组成正方形？
<gadget id="calculator">1 + 8</gadget>
<output>9</output>

<result>9</result>