If a room with a length of 5 meters and a width of 4 meters is paved with floor tiles with a side length of 2 decimeters, how many pieces do you need?
把一个长5米，宽4米的房间，用边长2分米的地砖铺地，要多少块．
<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) * (1/5)</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">4 / (1/25)</gadget>
<output>100</output>

<gadget id="calculator">5 * 100</gadget>
<output>500</output>

<result>500</result>