How many kilowatt-hours can the users of this building save in total in September? (After switching to energy-saving lamps, each household can save 1.28 kWh of electricity per day. There are 30 households in the building.)
九月份该楼用户一共可节约用电多少千瓦时？(改用节能灯后，每户每天可节省用电1.28千瓦时．楼内有30户居民．)
<gadget id="calculator">1.28 * 30 * 30</gadget>
<output>1_152</output>

<result>1_152</result>