The diameter of the semicircle is 2 cm, what is the circumference of the semicircle?
半圆的直径是2厘米，半圆的周长是多少．
<gadget id="calculator">2 / 2</gadget>
<output>1</output>

<gadget id="calculator">3.14 * 1</gadget>
<output>3.14</output>

<gadget id="calculator">3.14 + 2</gadget>
<output>5.14</output>

<result>5.14</result>