Uncle Li piles up four logs with a radius of 8dm and binds them in a circle, how much dm rope is needed. (neglected at joints)
李叔叔把四根半径8dm的圆木，摞起来捆一圈，需要多少dm绳子．(接头处忽略不计)
<gadget id="calculator">2 * 3.14 * 8</gadget>
<output>50.24</output>

<gadget id="calculator">8 * 2 * 4</gadget>
<output>64</output>

<gadget id="calculator">50.24 + 64</gadget>
<output>114.24</output>

<result>114.24</result>