For a round bucket, the mouth and the bottom of the bucket are the same size, and the outer diameter is 6dm. Now use iron wire to fasten the mouth and bottom of the bucket respectively. How much iron wire is needed at least? (neglected at joints)
一个圆形的水桶，桶口和桶底都是一样大小的圆形，外直径是6dm，现在用铁丝分别将桶口和桶底箍紧，至少需要多少铁丝？(接头处忽略不计)
<gadget id="calculator">3.14 * 6 * 2</gadget>
<output>37.68</output>

<result>37.68</result>