It takes 2,000 pieces to pave the classroom with square bricks with a side length of 30 cm. Now it is changed to use square bricks with a side length of 50 cm. How many pieces are needed? (in proportion)
用边长是30厘米的方砖给教室铺地，需要2000块，现改成用边长是50厘米的方砖，需要多少块？(用比例)
<gadget id="calculator">30 * 30 * 2_000</gadget>
<output>1_800_000</output>

<gadget id="calculator">50 * 50</gadget>
<output>2_500</output>

<gadget id="calculator">1_800_000 / 2_500</gadget>
<output>720</output>

<result>720</result>