The classroom is 8 meters long, 6 meters wide, and 4 meters high, with doors and windows covering an area of 18 square meters. To paint the surrounding walls and ceiling, an average of 250 grams of paint is used per square meter. How many kilograms of paint are needed in total?
教室长8米，宽6米，高4米，门窗面积18平方米．粉刷四周墙壁和顶棚，平均每平方米用涂料250克，一共需要多少千克涂料？
<gadget id="calculator">8 * 6</gadget>
<output>48</output>

<gadget id="calculator">8 * 4</gadget>
<output>32</output>

<gadget id="calculator">6 * 4</gadget>
<output>24</output>

<gadget id="calculator">48 + 32 + 24</gadget>
<output>104</output>

<gadget id="calculator">104 * 2</gadget>
<output>208</output>

<gadget id="calculator">208 - 48 - 18</gadget>
<output>142</output>

<gadget id="calculator">250 / 1_000</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">142 * (1/4)</gadget>
<output>71/2 = around 35.5</output>

<result>71/2 = around 35.5</result>