There are five different boxes and seven different balls.All the seven balls are to be distributed in these boxes.The number of ways can they be distributed so that no box remains empty are

There are four different boxes and six different balls. All the six balls are to be distributed in the four boxes placed in row.So that any box can received any number of balls in how many ways can these balls be distributed so that no box is empty.

Five balls are to be placed in three boxes in how many diff. ways can be placed the balls so that no box remain empty if .