Use a 6.28 decimeter iron wire to bend a circular iron ring (not counting the joint), what is the area of the iron ring in square decimeters?
用一根6.28分米的铁丝弯成一个圆形铁环(接口处不计)，铁环的面积是多少平方分米．
<gadget id="calculator">6.28 / 3.14 / 2</gadget>
<output>1</output>

<gadget id="calculator">1 ** 2</gadget>
<output>1</output>

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

<result>3.14</result>