If the circumference of a circle is 6.28 decimeters, what is its area in square decimeters?
一个圆的周长是6.28分米，那么它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>