A classroom is 8 meters long, 6 meters wide, and 3 meters high, with a total area of 15.6 square meters of doors and windows. To paint the walls and ceiling of the classroom, if 0.25 kilograms of paint is used per square meter, how many kilograms of paint are needed in total?
一间教室长8米、宽6米、高3米，门窗面积共15.6平方米．要粉刷教室的四壁和顶棚，如果每平方米用涂料0.25千克，共需要涂料多少千克？
<gadget id="calculator">8 * 6</gadget>
<output>48</output>

<gadget id="calculator">8 * 3 * 2</gadget>
<output>48</output>

<gadget id="calculator">6 * 3 * 2</gadget>
<output>36</output>

<gadget id="calculator">36 - 15.6</gadget>
<output>20.4</output>

<gadget id="calculator">48 + 48 + 20.4</gadget>
<output>116.4</output>

<gadget id="calculator">0.25 * 116.4</gadget>
<output>29.1</output>

<result>29.1</result>