An auditorium with a length of 20 meters and a width of 15 meters needs to be paved with floor tiles. The floor tiles are squares with a side length of 5 decimeters. How many floor tiles should be bought at least?
一个长20米，宽15米的礼堂中要铺地砖，地砖是边长为5分米的正方形，则至少要买多少块地砖？
<gadget id="calculator">5 / 10</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">15 / (1/4)</gadget>
<output>60</output>

<gadget id="calculator">20 * 60</gadget>
<output>1_200</output>

<result>1_200</result>