classroom with a length of 9 meters, a width of 6 meters, and a height of 4 meters, paint its roof and walls, deduct the area of doors and windows of 24 meters, if 200 grams of wall powder is used per square meter, how many kilograms of wall powder are needed in total?
一间长9米，宽6米，高4米的教室，粉刷它的屋顶和墙壁，扣除门窗面积24米，如果每平方米用刷墙粉200克，一共需要刷墙粉多少千克？
<gadget id="calculator">9 * 6</gadget>
<output>54</output>

<gadget id="calculator">9 * 4</gadget>
<output>36</output>

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

<gadget id="calculator">54 + 36 + 24</gadget>
<output>114</output>

<gadget id="calculator">114 * 2</gadget>
<output>228</output>

<gadget id="calculator">228 - 54 - 24</gadget>
<output>150</output>

<gadget id="calculator">200 / 10_000</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">150 * (1/50)</gadget>
<output>3</output>

<result>3</result>