There are 6 cuboid wooden columns in the hall, each 4.5m high and 0.5m long and wide. Now paint them. If 0.4kg of paint is needed per square meter, how many kilograms of paint are needed in total?
大厅中有6根长方体木柱，每根高4.5m，长和宽都是0.5m．现在把它们油漆，如果每平方米需油漆0.4kg，共需要油漆多少千克？
<gadget id="calculator">0.5 * 4</gadget>
<output>2</output>

<gadget id="calculator">2 * 4.5</gadget>
<output>9</output>

<gadget id="calculator">9 * 6 * 0.4</gadget>
<output>21.6</output>

<result>21.6</result>