A sprinkler irrigation device in the lawn of Yiling Square can spray up to 4 meters, and how many square meters of lawn can it irrigate once it rotates once.
夷陵广场草坪里一个喷灌装置最远能喷4米，它旋转一周能浇灌多少平方米草坪．
<gadget id="calculator">4 ** 2</gadget>
<output>16</output>

<gadget id="calculator">3.14 * 16</gadget>
<output>50.24</output>

<result>50.24</result>