A circular part has an outer diameter of 16 cm and an inner radius of 5 cm. What is the area of the part in square centimeters?
一个环形零件，它的外直径是16厘米，它的内半径是5厘米，这个零件的面积是多少平方厘米？
<gadget id="calculator">16 / 2</gadget>
<output>8</output>

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

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">64 - 25</gadget>
<output>39</output>

<gadget id="calculator">3.14 * 39</gadget>
<output>122.46</output>

<result>122.46</result>