Wrap a colored ribbon around a pen barrel with a radius of 5cm, and the knot is 5cm. How many cm of colored ribbon is required?
在一个半径为5cm的笔桶上围一圈彩带，结头处为5cm，共需彩带多少cm？
<gadget id="calculator">3.14 * 2 * 5</gadget>
<output>31.4</output>

<gadget id="calculator">31.4 + 5</gadget>
<output>36.4</output>

<result>36.4</result>