A circular machine part spacer has an outer radius of 5 cm and an inner radius of 2 cm. What is the area of this spacer in square centimeters?
一个环形的机器零件垫片，外半径是5厘米，内半径是2厘米．这个垫片的面积是多少平方厘米？
<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">25 - 4</gadget>
<output>21</output>

<gadget id="calculator">3.14 * 21</gadget>
<output>65.94</output>

<result>65.94</result>