Lingling's house has a room with a length of 4 meters and a width of 3.5 meters. The floor is paved with square bricks with a side length of 0.5 meters. How many bricks are needed at least?
玲玲家有一个房间长4米，宽3.5米，用边长为0.5米的方砖铺地，至少需要多少块？
<result>48</result>