If the diameter of a circle is enlarged by 4 times, how many times will the area be enlarged?
一个圆的直径扩大4倍，面积扩大多少倍．
<gadget id="calculator">2 * 4</gadget>
<output>8</output>

<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<result>16</result>