The radius of the large circle is twice the radius of the small circle. If the radius of the small circle is 3 cm, what is the area of the large circle?
大圆的半径是小圆半径的2倍，如果小圆的半径是3cm，那么大圆的面积是多少．
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">6 ** 2</gadget>
<output>36</output>

<gadget id="calculator">3.14 * 36</gadget>
<output>113.04</output>

<result>113.04</result>