Cut a ring out of iron sheet, the radius of the inner circle is 4 cm, and the width of the ring is 2 cm. What is its area?
用铁皮剪成一个圆环，内圆半径4厘米，环宽2厘米，它的面积是多少？
<gadget id="calculator">4 + 2</gadget>
<output>6</output>

<gadget id="calculator">6 ** 2</gadget>
<output>36</output>

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

<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<gadget id="calculator">113.04 - 50.24</gadget>
<output>62.8</output>

<result>62.8</result>