A building has 5 floors, and each floor has 6 households. If each household saves 1.3 kilowatt-hours of electricity on average, how much electricity can this building save per month?
一幢楼有5层，每层有6户居民，如果平均每户节约用电1.3度，这幢楼每月共节约用电多少度？
<gadget id="calculator">5 * 6 * 1.3</gadget>
<output>39</output>

<result>39</result>