It costs 900 yuan to pave a small room with square bricks with a side length of 0.2 meters. If you use square bricks with a side length of 0.3 meters instead, how many pieces will you need? (Solve with ratio)
用边长0.2米的方砖给一间小房间铺地，要900块，如果改用边长0.3米的方砖来铺，需要多少块？(用比例解)
<gadget id="calculator">0.2 * 0.2 * 900</gadget>
<output>36</output>

<gadget id="calculator">0.3 * 0.3</gadget>
<output>0.09</output>

<gadget id="calculator">36 / 0.09</gadget>
<output>400</output>

<result>400</result>