The radius of a semicircular pond is 10 meters, what is the perimeter of the pond?
一个半圆形池塘的半径是10米，这个池塘的周长是多少？
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">2 * 3.14 * 5</gadget>
<output>31.4</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<gadget id="calculator">31.4 + 20</gadget>
<output>51.4</output>

<result>51.4</result>