Use 7dm long iron wire to form a circle, and there is 0.72dm left, what is the area of this circle in square decimeters?
用7dm长的铁丝围成一个圆，还剩0.72dm，这个圆的面积是多少平方分米？
<gadget id="calculator">7 - 0.72</gadget>
<output>6.28</output>

<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>