Sound travels about 1 kilometer in 3 seconds in the air, the speed of light is about 300,000 kilometers per second, and the speed of sound is about the speed of light ((())/(())).
声音在空气中3秒钟大约传1千米，光的速度每秒大约300000千米，声音的速度大约是光速的((())/(()))．
<gadget id="calculator">1 / 3 / 300_000</gadget>
<output>1/900_000 = around 0.000001</output>

<result>1/900_000 = around 0.000001</result>