A laser signal sent from the earth to the moon receives a signal reflected from the moon after about 2.56 seconds. Given that the speed of light is 300,000 km/s, what is the distance from the moon to the earth at this time?
从地球上向月球发射的一个激光信号，经过约2.56秒收到从月球反射回来的信号．已知光速是30万千米/秒，算一算这时月球到地球的距离是多少？
<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>