For a round bucket, the mouth and the bottom of the bucket are the same size circle, and the outer diameter is 6dm. Now use iron wire to tie the mouth and the bottom of the bucket respectively, how many decimeters of iron wire are needed at least? (neglected at joints)
一个圆形水桶，桶口和桶底都是一样大小的圆，外直径是6dm，现在用铁丝分别将桶口和桶底各打一道箍，至少需要多少分米铁丝？(接头处忽略不计)
<gadget id="calculator">3.14 * 6 * 2</gadget>
<output>37.68</output>

<result>37.68</result>