ring has an outer radius of 8 cm and an inner radius of 5 cm. What is the area of the ring in square centimeters?
一个圆环，外圆半径是8厘米，内圆半径是5厘米，这个圆环的面积是多少平方厘米？
<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>