A rope is 4 meters long. One end of the rope is tied to a sheep, and the other end is fixed on the grass with a stake. How many meters does it take for the sheep to walk around the stake?
一根绳子长为4米，绳的一头栓一只羊，另一头用木桩固定在草地上．羊绕木桩走一圈要走多少米？
<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<gadget id="calculator">3.14 * 8</gadget>
<output>25.12</output>

<result>25.12</result>