The floor of the school cafeteria should be paved with floor tiles. If square tiles with an area of 9 square decimeters are used, 800 tiles will just cover it. If square tiles with a side length of 4 decimeters are used, how many tiles are needed?
学校食堂地面要铺设地砖，如果用面积9平方分米的方砖，800块正好铺满，如果用边长是4分米的方砖，需要多少块？
<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<gadget id="calculator">9 / 16</gadget>
<output>9/16 = around 0.5625</output>

<gadget id="calculator">800 * (9/16)</gadget>
<output>450</output>

<result>450</result>