Cut a square with a side length of 2 decimeters into the largest circle, then the circumference of this circle = how much.
把边长为2分米的正方形剪成一个最大的圆，则这个圆的周长=多少．
<gadget id="calculator">3.14 * 2</gadget>
<output>6.28</output>

<result>6.28</result>