There is a circular open space with a diameter of 24 meters in the park. It is planned to build a flowerbed with a radius of 8 meters in the center of it. The remaining part is paved with cement. Find the area of the cement floor.
公园里有一块直径是24米的圆形空地，计划在它的中央修一个半径为8米的花圃，剩余部分铺水泥，求水泥地面的面积．
<gadget id="calculator">24 / 2</gadget>
<output>12</output>

<gadget id="calculator">12 ** 2</gadget>
<output>144</output>

<gadget id="calculator">8 ** 2</gadget>
<output>64</output>

<gadget id="calculator">144 - 64</gadget>
<output>80</output>

<gadget id="calculator">3.14 * 80</gadget>
<output>251.2</output>

<result>251.2</result>