After installing a water-saving valve in a residential building, the average household saves 2.5 tons of water per month. According to this calculation, how many tons of water can be saved in a quarter for the 54 households in the whole building?
一栋居民楼安装了节水阀门以后，平均每户每月节约用水2.5吨．照这样计算，全楼54户居民，一个季度可以节约用水多少吨？
<gadget id="calculator">2.5 * 54 * 3</gadget>
<output>405</output>

<result>405</result>