A circular flower bed has a diameter of 4 meters, and a 0.5-meter gravel road is paved around it. What is the area of the gravel road in square meters?
一个圆形花坛，直径是4米，沿着它周围铺一条0.5米的石子路，求石子路的面积是多少平方米？
<gadget id="calculator">4 / 2</gadget>
<output>2</output>

<gadget id="calculator">2 + 0.5</gadget>
<output>2.5</output>

<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>