A piece of wood with a radius of 3 decimeters needs to be wound 3 times with a rope. What is the minimum length of the rope?
一个半径是3分米的木头，要用一条绳子绕它3圈，这条绳子至少要有多长？
<gadget id="calculator">3.14 * 2 * 3 * 3</gadget>
<output>56.52</output>

<result>56.52</result>