If a circle has a diameter of 6 cm, what is its area?
一个圆的直径为6厘米，它的面积是多少π平方厘米．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<result>9</result>