The floor of the multifunctional classroom is paved with square bricks with an area of 9 square decimeters, and 450 square bricks are exactly covered. If you use square bricks with a side length of 5 decimeters instead, how many pieces are needed?
多功能教室用面积9平方分米的方砖铺地面，450块正好铺满．如果改用边长是5分米的方砖铺，需要多少块？
<gadget id="calculator">5 * 5</gadget>
<output>25</output>

<gadget id="calculator">450 / 25</gadget>
<output>18</output>

<gadget id="calculator">9 * 18</gadget>
<output>162</output>

<result>162</result>