If the radius of a circle is changed from 10 meters to 11 meters, how much does the circumference of the circle increase in meters?
圆的半径由10米变为11米，圆的周长增加多少米．
<gadget id="calculator">3.14 * 11 * 2</gadget>
<output>69.08</output>

<gadget id="calculator">3.14 * 10 * 2</gadget>
<output>62.8</output>

<gadget id="calculator">69.08 - 62.8</gadget>
<output>6.28</output>

<result>6.28</result>