Put three iron hoops on the periphery of a cylindrical wooden barrel with an outer diameter of 30 decimeters, and use 0.2 meters for each iron hoop joint. How long is the iron bar needed to tie these iron hoops?
在一个外直径30分米的圆柱形木桶外围打上三道铁箍，每道铁箍接头处用0.2米，打这些铁箍需多长的铁条？
<gadget id="calculator">3.14 * 3</gadget>
<output>9.42</output>

<gadget id="calculator">9.42 + 0.2</gadget>
<output>9.62</output>

<gadget id="calculator">9.62 * 3</gadget>
<output>28.86</output>

<result>28.86</result>