A wire surrounds a rectangle with a length of 12 cm and a width of 6 cm. If the wire is formed into a square, what is the side length of the square?
一条铁丝围成一个长方形，长是12厘米，宽是6厘米．如果将这条铁丝围成一个正方形，这个正方形的边长是多少厘米？
<gadget id="calculator">12 + 6</gadget>
<output>18</output>

<gadget id="calculator">18 * 2</gadget>
<output>36</output>

<gadget id="calculator">36 / 4</gadget>
<output>9</output>

<result>9</result>