If the diameter of a circle increases by 3, how many times does its area increase.
一个圆的直径扩大3，它的面积扩大多少倍倍．
<gadget id="calculator">2 / 1</gadget>
<output>2</output>

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

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<gadget id="calculator">6 / 2</gadget>
<output>3</output>

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

<gadget id="calculator">9 / 12.56</gadget>
<output>0.716561</output>

<gadget id="calculator">12.56 * 0.716561</gadget>
<output>9.000006</output>

<result>9.000006</result>