The diameter of a circular radar screen is 40 cm, what is its area in square centimeters?
一个雷达圆形屏幕的直径是40厘米，它的面积是多少平方厘米？
<gadget id="calculator">40 / 2</gadget>
<output>20</output>

<gadget id="calculator">20 ** 2</gadget>
<output>400</output>

<gadget id="calculator">3.14 * 400</gadget>
<output>1_256</output>

<result>1_256</result>