If you use rectangular bricks with a length of 30 cm and a width of 24 cm to pave a room, 900 bricks are needed; if the room is paved with square bricks with a side length of 20 cm, how many bricks are needed?
用长30厘米，宽24厘米的长方形砖块铺房间，需要900块；如果改用边长20厘米的方砖铺这个房间，需要多少块？
<gadget id="calculator">30 * 24 * 900</gadget>
<output>648_000</output>

<gadget id="calculator">20 * 20</gadget>
<output>400</output>

<gadget id="calculator">648_000 / 400</gadget>
<output>1_620</output>

<result>1_620</result>