To pave a classroom, 450 pieces of square bricks with a side length of 4 decimeters are needed. If the square bricks with a side length of 3 decimeters are used instead, how many pieces are needed? (Solve with ratio)
铺一间教室，用边长4分米的方砖需要450块，如果改用边长3分米的方砖，需要多少块？(用比例解)
<gadget id="calculator">4 * 4 * 450</gadget>
<output>7_200</output>

<gadget id="calculator">3 * 3</gadget>
<output>9</output>

<gadget id="calculator">7_200 / 9</gadget>
<output>800</output>

<result>800</result>