A house is paved with square bricks with an area of 9 square decimeters, and 200 pieces are needed. If the square bricks with an area of 4 square decimeters are used instead, how many square bricks are needed?
一间房子铺地砖，用面积是9平方分米的方砖，需要200块，如果改用面积是4平方分米的方砖，需要多少块？
<gadget id="calculator">9 * 200</gadget>
<output>1_800</output>

<gadget id="calculator">1_800 / 4</gadget>
<output>450</output>

<result>450</result>