The length and width of the bottom of Xiao Ming's bedroom are 5 meters and 4 meters respectively, and the floor is covered with square floor tiles with a side length of 50 cm. How many such floor tiles are needed at least?
小明卧室底面的长和宽分别是5米和4米，用边长是50厘米的正方形地砖铺满整个地面，至少需要几块这样的地砖？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) * (1/2)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">4 / (1/4)</gadget>
<output>16</output>

<gadget id="calculator">5 * 16</gadget>
<output>80</output>

<result>80</result>