A group of $$40$$ students are on a field trip at the river. In order to cross the river, their teacher, Mr. Linder, is able to send at most $$6$$ students on one boat at a time. How many times at least does he need to send all the students across the river using only one boat? 
Overseas Competition->Knowledge Point->Word Problem Modules->Unitary Method Problems->Applying Multiplication and Division