Cut a circle into an approximate rectangle, if the perimeter of the rectangle is 24.84 decimeters, then how many decimeters is the perimeter of the circle.
把一个圆剪拼成一个近似的长方形，如果长方形的周长为24.84分米，那么这个圆的周长是多少分米．
<gadget id="calculator">2 * 3.14</gadget>
<output>6.28</output>

<gadget id="calculator">2 + 6.28</gadget>
<output>8.28</output>

<gadget id="calculator">24.84 / 8.28</gadget>
<output>3</output>

<gadget id="calculator">2 * 3 * 3.14</gadget>
<output>18.84</output>

<result>18.84</result>