A cylinder has a base circumference of 3.14 decimeters and a height of 0.3 decimeters, what is the area of the base in square decimeters?
一个圆柱体，底面周长3.14分米，高0.3分米，底面积是多少平方分米．
<gadget id="calculator">3.14 / 3.14 / 2</gadget>
<output>0.5</output>

<gadget id="calculator">0.5 ** 2</gadget>
<output>0.25</output>

<gadget id="calculator">3.14 * 0.25</gadget>
<output>0.785</output>

<result>0.785</result>