Xiao Ming cuts a semicircular piece of paper with a diameter of 20 cm. What is its circumference in cm?
小明剪了一张直径为20厘米的半圆形纸片，它的周长是多少厘米．
<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">3.14 * 10</gadget>
<output>31.4</output>

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

<result>51.4</result>