The machine factory produces a ring-shaped machine part with an outer radius of 2.5 cm and an inner radius of 2 cm. What is the area of this ring-shaped part in square centimeters?
机厂生产一种环形机器零件，外圆半径2.5厘米，内圆半径2厘米，这个环形零件的面积是多少平方厘米？
<gadget id="calculator">2.5 ** 2</gadget>
<output>6.25</output>

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

<gadget id="calculator">6.25 - 4</gadget>
<output>2.25</output>

<gadget id="calculator">3.14 * 2.25</gadget>
<output>7.065</output>

<result>7.065</result>