Use square floor tiles with a side length of 20cm to pave a sidewalk with a length of 18 meters and a width of 15 meters. How many such floor tiles are needed at least?
用边长为20cm的正方形地砖铺一段长是18米，宽是15米的人行道路面，至少需要多少块这样的地砖？
<gadget id="calculator">20 / 100</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">15 / (1/25)</gadget>
<output>375</output>

<gadget id="calculator">18 * 375</gadget>
<output>6_750</output>

<result>6_750</result>