A teaching building with 4 floors and 12 classrooms on each floor. If 12 fluorescent tubes are to be installed in each classroom, how many fluorescent tubes should be purchased at least?
一幢教学楼，共4层，每层有12个教室．如果每个教室要安装日光灯管12支，至少应买多少支日光灯管？
<result>240</result>