The diameter of a circle is 6dm, what is its area dm**2.
一个圆的直径为6dm，其面积为多少dm**2．
<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>