The radius of a circular island is 20 meters, the middle is a circular flower bed with a radius of 5 meters, and the rest is a lawn; how many square meters does the lawn cover?
一个圆环形岛的半径是20米，中间是一个半径5米的圆形花坛，其它地方是草坪；草坪的占地面积是多少平方米？
<gadget id="calculator">20 ** 2</gadget>
<output>400</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">400 - 25</gadget>
<output>375</output>

<gadget id="calculator">3.14 * 375</gadget>
<output>1_177.5</output>

<result>1_177.5</result>