The length of a room is 6 meters, the width is 3.5 meters, and the height is 3 meters. The area of doors and windows is 8 square meters. Now we need to paint the walls and ceiling of this room with cement. If 3.5 kilograms of cement is needed per square meter, how many kilograms of cement are needed to paint this classroom?
一个房间的长6米，宽3.5米，高3米，门窗面积是8平方米．现在要把这个房间的四壁和顶面粉刷水泥，如果每平方米需水泥3.5千克，粉刷这间教室共需水泥多少千克？
<gadget id="calculator">6 * 3 * 2</gadget>
<output>36</output>

<gadget id="calculator">3.5 * 3 * 2</gadget>
<output>21</output>

<gadget id="calculator">6 * 3.5</gadget>
<output>21</output>

<gadget id="calculator">21 - 8</gadget>
<output>13</output>

<gadget id="calculator">36 + 21 + 13</gadget>
<output>70</output>

<gadget id="calculator">3.5 * 70</gadget>
<output>245</output>

<result>245</result>