The area of a circle is 94.2 square centimeters. If the radius of the circle is doubled, what is the area of the circle?
一个圆的面积是94.2平方厘米，若把这个圆的半径扩大2倍，这个圆的面积是多少．
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">94.2 * 4</gadget>
<output>376.8</output>

<result>376.8</result>