If the diameter of a semicircle is 5 cm, what is its circumference in cm?
一个半圆的直径是5厘米，它的周长是多少厘米．
<gadget id="calculator">5 / 2</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">3.14 * (5/2)</gadget>
<output>7.85</output>

<gadget id="calculator">7.85 + 5</gadget>
<output>12.85</output>

<result>12.85</result>