A classroom should be paved with square bricks. It takes 400 square bricks with an area of 0.15 square meters. If the square bricks with a side length of 0.2 meters are used instead, how many bricks are needed?
一间教室要用方砖铺地．用面积是0.15平方米的方砖需要400块，如果改用边长是0.2米的方砖，需要多少块？
<gadget id="calculator">0.2 * 0.2</gadget>
<output>0.04</output>

<gadget id="calculator">400 / 0.04</gadget>
<output>10_000</output>

<gadget id="calculator">0.15 * 10_000</gadget>
<output>1_500</output>

<result>1_500</result>