classroom is 10 meters long, 6 meters wide, and 4 meters high. It is necessary to paint the ceiling and surrounding walls of the auditorium. Excluding the door and window area of 20 square meters, an average of 0.5 kilograms of paint is used per square meter. How many kilograms of paint are needed in total?
一间教室长10米，宽6米，高4米，要粉刷礼堂的顶棚和四周墙壁，除去门窗面积20平方米，平均每平方米用涂料0.5千克，一共需涂料多少千克？
<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">40 + 24</gadget>
<output>64</output>

<gadget id="calculator">64 * 2</gadget>
<output>128</output>

<gadget id="calculator">128 - 20</gadget>
<output>108</output>

<gadget id="calculator">60 + 108</gadget>
<output>168</output>

<gadget id="calculator">168 * 0.5</gadget>
<output>84</output>

<result>84</result>