There is an automatic rotary sprinkler irrigation device on the grassland with a sprinkler radius of 15m. How much grassland can it irrigate?
草地上有一个自动旋转喷灌装置，喷灌半径为15m，它能喷灌多大面积的草地？
<gadget id="calculator">3.14 * 15 * 15</gadget>
<output>706.5</output>

<result>706.5</result>