To pave the floor of a classroom with square bricks, 2000 pieces are needed to pave the floor with square bricks with a side length of 15 cm. If the floor is paved with square bricks with a side length of 25 cm, how many pieces of this kind of square bricks are needed? (Use proportions to solve.)
用方砖铺一间教室的地面，用边长15厘米的方砖铺地，需要2000块，如果改用边长为25厘米的方砖铺地，那么需要该种方砖多少块？(用比例解．)
<gadget id="calculator">15 * 15 * 2_000</gadget>
<output>450_000</output>

<gadget id="calculator">25 * 25</gadget>
<output>625</output>

<gadget id="calculator">450_000 / 625</gadget>
<output>720</output>

<result>720</result>