What is the perimeter in cm of a semicircle with a diameter of 10 cm.
直径是10cm的半圆的周长是多少cm．
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">3.14 * 5</gadget>
<output>15.7</output>

<gadget id="calculator">15.7 + 10</gadget>
<output>25.7</output>

<result>25.7</result>