The school used square bricks to pave the floor of the conference room. Originally, it was planned to use square bricks with a side length of 6 decimeters, which cost 320 yuan. Now switch to square bricks with a side length of 4 decimeters, how many pieces are needed?
学校用方砖铺会议室的地面，原来打算用边长6分米的方砖，需要320块．现在改用边长4分米的方砖，需要多少块？
<gadget id="calculator">4 * 4</gadget>
<output>16</output>

<gadget id="calculator">320 / 16</gadget>
<output>20</output>

<gadget id="calculator">6 * 6 * 20</gadget>
<output>720</output>

<result>720</result>