A circular iron sheet has an inner radius of 0.35 meters and an outer radius of 0.65 meters. What is the area of the annular iron sheet in square meters?
一个环形铁皮，内圆半径是0.35米，外圆半径是0.65米，环形铁皮的面积是多少平方米？
<gadget id="calculator">0.65 ** 2</gadget>
<output>0.4225</output>

<gadget id="calculator">0.35 ** 2</gadget>
<output>0.1225</output>

<gadget id="calculator">0.4225 - 0.1225</gadget>
<output>0.3</output>

<gadget id="calculator">3.14 * 0.3</gadget>
<output>0.942</output>

<result>0.942</result>