30% of a 600-kilometer road has been built, how many kilometers have been built?
修一条长600千米的公路，已修了30%，修了多少千米？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">600 * (3/10)</gadget>
<output>180</output>

<result>180</result>