If a classroom is paved with square floor tiles, it takes 400 pieces to choose a side length of 3 decimeters. If it is replaced with a side length of 4 decimeters, how many floor tiles do you need to prepare?
一间教室铺正方形地砖，选用边长3分米的要用400块，如果换成边长4分米的地砖，需要准备地砖多少块？
<gadget id="calculator">3 * 3 * 400</gadget>
<output>3_600</output>

<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<gadget id="calculator">3_600 / 16</gadget>
<output>225</output>

<result>225</result>