Bind 4 logs with a cross-sectional diameter of 20 centimeters together. If the joints are not considered, how many centimeters of iron wire should be used for one circle at least?
把横截面直径都是20厘米的4根圆木捆在一起，如果不考虑接头，捆一圈至少要用多少厘米铁丝？
<gadget id="calculator">3.14 * 20</gadget>
<output>62.8</output>

<gadget id="calculator">20 * 4</gadget>
<output>80</output>

<gadget id="calculator">62.8 + 80</gadget>
<output>142.8</output>

<result>142.8</result>