A classroom is 10 meters long, 6 meters wide, and 4 meters high. The area excluding doors and windows is 19 square meters. If the walls and ceiling of the classroom are to be painted, if 0.5 kilograms of paint is used per square meter, how many kilograms of paint are needed?
一间教室长10米，宽6米，高4米，扣除门和窗的面积19平方米，要粉刷教室的四壁和顶棚，如果每平方米用涂料0.5千克，共需要涂料多少千克？
<gadget id="calculator">10 * 6</gadget>
<output>60</output>

<gadget id="calculator">10 * 4</gadget>
<output>40</output>

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

<gadget id="calculator">60 + 40 + 24</gadget>
<output>124</output>

<gadget id="calculator">124 * 2</gadget>
<output>248</output>

<gadget id="calculator">248 - 60 - 19</gadget>
<output>169</output>

<gadget id="calculator">169 * 0.5</gadget>
<output>84.5</output>

<result>84.5</result>