If the diameter of a circle is 20 centimeters, what is the area of the circle in square centimetres? (π takes 3.14)
已知圆的直径为20厘米，则圆的面积为多少平方厘米．(π取3.14)
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<result>314</result>