For a rectangular living room with a length of 4 meters and a width of 3 meters, at least how many small square colored bricks with an area of 1 square decimeter should be used to just cover it.
长是4米，宽3米的长方形客厅，至少要用多少个面积是1平方分米的小正方形彩色砖才能正好铺满．
<gadget id="calculator">4 * 10</gadget>
<output>40</output>

<gadget id="calculator">3 * 10</gadget>
<output>30</output>

<gadget id="calculator">30 / 1</gadget>
<output>30</output>

<gadget id="calculator">40 * 30</gadget>
<output>1_200</output>

<result>1_200</result>