To bind three cylindrical steel pipes with a diameter of 2 cm together, at least how many centimeters of rope are needed (neglecting the connection).
把三根直径都是2厘米的圆柱形钢管捆绑在一起，至少需要多少厘米的绳子(接着处忽略不计)．
<gadget id="calculator">3.14 * 2</gadget>
<output>6.28</output>

<gadget id="calculator">2 * 3</gadget>
<output>6</output>

<gadget id="calculator">6.28 + 6</gadget>
<output>12.28</output>

<result>12.28</result>