There is an automatic sprinkler in the garden in the middle of the street. The radius of the sprinkler is 9 meters. How many square meters can the grass be watered by turning the sprinkler in one circle?
街心花园内有一自动喷灌机，喷水的半径是9米，喷头转动一圈可以浇灌草地的面积为多少平方米？
<gadget id="calculator">9 ** 2</gadget>
<output>81</output>

<gadget id="calculator">3.14 * 81</gadget>
<output>254.34</output>

<result>254.34</result>