The length of a classroom is 10 meters, the width is 8 meters, and the height is 4 meters. It is necessary to paint the roof and four walls of the classroom. The area of the classroom is 28 square meters, excluding doors, windows and blackboards. If 0.5 kilograms of paint is used per square meter, how many kilograms are needed in total? paint?
一间教室的长是10米，宽是8米，高是4米，要粉刷教室的屋顶和四面墙壁，除去门窗和黑板面积28平方米，如果每平方米用油漆0.5千克，一共需要多少千克油漆？
<gadget id="calculator">10 * 8</gadget>
<output>80</output>

<gadget id="calculator">8 * 4 * 2</gadget>
<output>64</output>

<gadget id="calculator">10 * 4 * 2</gadget>
<output>80</output>

<gadget id="calculator">80 + 64 + 80</gadget>
<output>224</output>

<gadget id="calculator">224 - 28</gadget>
<output>196</output>

<gadget id="calculator">196 * 0.5</gadget>
<output>98</output>

<result>98</result>