After switching to energy-saving lamps, each household can save 1.2 kWh of electricity per day. There are 50 households in the building. How many kilowatt-hours can the users of this building save in total in September?
改用节能灯后，每户每天可节省用电1.2千瓦时．楼内有50户居民．九月份该楼用户一共可节约用电多少千瓦时？
<gadget id="calculator">1.2 * 50 * 30</gadget>
<output>1_800</output>

<result>1_800</result>