The table top of the ping-pong table is a rectangle. Its length is about 27dm and its area is about 405dm**2. What is its perimeter?
乒乓桌的桌面是一个长方形，它的长约27dm，面积约405dm**2，它的周长是多少？
<gadget id="calculator">405 / 27</gadget>
<output>15</output>

<gadget id="calculator">27 + 15</gadget>
<output>42</output>

<gadget id="calculator">42 * 2</gadget>
<output>84</output>

<result>84</result>