The diameter of a semicircle is 1 cm, what is the circumference of the semicircle?
一个半圆的直径是1厘米，求这个半圆的周长是多少厘米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">3.14 * (1/2)</gadget>
<output>1.57</output>

<gadget id="calculator">1.57 + 1</gadget>
<output>2.57</output>

<result>2.57</result>