A square iron plate with a side length of 6 decimeters is used to make the largest circular cylinder head. What is the area of the cylinder head in square decimeters?
一块边长是6分米的正方形铁板，要做一个最大的圆形缸盖，这个缸盖的面积是多少平方分米．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">3.14 * 9</gadget>
<output>28.26</output>

<result>28.26</result>