A circular fountain has a radius of 10 meters, and a railing is placed 0.5 meters away from the edge of the pool. How many meters is the railing?
一个圆形喷水池的半径10米，在离水池边0.5米的外面围上栏杆．栏杆长多少米？
<gadget id="calculator">10 + 0.5</gadget>
<output>10.5</output>

<gadget id="calculator">2 * 3.14 * 10.5</gadget>
<output>65.94</output>

<result>65.94</result>