laser signal is sent from the earth to the moon, and the return signal is received after 2.56 seconds. It is known that the speed of light is 300,000 km/s, how far is the earth from the moon at this time?
一次从地球上向月球发射激光信号，经过2.56秒收到返回信号．已知光速是30万千米/秒，这时地球离月球有多远？
<gadget id="calculator">2.56 / 2</gadget>
<output>1.28</output>

<gadget id="calculator">30 * 1.28</gadget>
<output>38.4</output>

<result>38.4</result>