Cut out the largest square from a rectangular plank with a length of 9 meters and a width of 6 meters. What is the perimeter of this square in meters?
在一块长9米，宽6米的长方形木板上截下一个最大的正方形，这个正方形的周长是多少米．
<gadget id="calculator">6 * 4</gadget>
<output>24</output>

<result>24</result>