Class 5 and 2 need to use paint to paint the classroom. It is known that the length, width and height of the classroom are 9 meters, 6 meters and 3 meters respectively. To paint the ceiling and four walls of the classroom, deduct the door and window area of 40 square meters, and need 0.5 kilograms of paint per square meter. How many kilograms of paint are needed to paint this classroom?
五2班要用涂料粉刷教室，已知教室的长宽高分别为9米、6米、3米．要粉刷教室的天花板和四面墙壁，扣除门窗面积40平方米，每平方米需要涂料0.5千克，粉刷这个教室需多少千克的涂料？
<gadget id="calculator">9 * 6</gadget>
<output>54</output>

<gadget id="calculator">6 * 3</gadget>
<output>18</output>

<gadget id="calculator">3 * 9</gadget>
<output>27</output>

<gadget id="calculator">54 + 18 + 27</gadget>
<output>99</output>

<gadget id="calculator">99 * 2</gadget>
<output>198</output>

<gadget id="calculator">198 - 54 - 40</gadget>
<output>104</output>

<gadget id="calculator">104 * 0.5</gadget>
<output>52</output>

<result>52</result>