There is a Ferris wheel, its radius is 30 meters, so how many square centimeters does it move on?
有一个摩天轮，它的半径是30米，那么它运转的面积是多少平方厘米．
<gadget id="calculator">30 ** 2</gadget>
<output>900</output>

<gadget id="calculator">3.14 * 900 * 10_000</gadget>
<output>28_260_000</output>

<result>28_260_000</result>