A circular iron plate has an inner radius of 8 cm and an outer radius of 10 cm. What is the area of this annular iron plate?
一个环形铁片，内圆半径是8厘米，外圆半径是10厘米，这个环形铁片的面积是多少？
<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">8 ** 2</gadget>
<output>64</output>

<gadget id="calculator">100 - 64</gadget>
<output>36</output>

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

<result>113.04</result>