Outside the circular flower bed with a diameter of 4 meters, pave a circular stone road with a width of 2 meters. What is the area of this gravel road?
在直径4米的圆形花坛外，铺一条环形石子路，路面宽2米．这条石子路的面积是多少？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

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

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

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

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

<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<gadget id="calculator">50.24 - 12.56</gadget>
<output>37.68</output>

<result>37.68</result>