In a circular open space with a diameter of 60 meters, a circular pool with a radius of 10 meters is planned to be built in the center of it, and the rest is paved with turf green space. What is the area of the turf green space in square meters?
在一块直径为60米的圆形空地，计划在它的中央修一个半径为10米的圆形水池，剩余部分铺草皮绿地，草皮绿地的面积是多少平方米．
<gadget id="calculator">60 / 2</gadget>
<output>30</output>

<gadget id="calculator">30 ** 2</gadget>
<output>900</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">900 - 100</gadget>
<output>800</output>

<gadget id="calculator">3.14 * 800</gadget>
<output>2_512</output>

<result>2_512</result>