If a circle with a diameter of 4 decimeters is drawn into a rectangle, what is the perimeter of the rectangle?
将一个直径是4分米的圆拉成一个长方形，这个长方形的周长是多少分米．
<gadget id="calculator">3.14 * 4</gadget>
<output>12.56</output>

<result>12.56</result>