Bind 2 logs with a cross-sectional diameter of 20 cm with iron wire (not counting the joints), and how many centimeters of iron wire is needed to tie a circle at least.
用铁丝把2根横截面直径为20厘米的圆木捆在一起(不计接头)，捆一圈到少需要多少厘米长的铁丝．
<gadget id="calculator">3.14 * 20</gadget>
<output>62.8</output>

<gadget id="calculator">20 * 2</gadget>
<output>40</output>

<gadget id="calculator">62.8 + 40</gadget>
<output>102.8</output>

<result>102.8</result>