There are 6 letters and 3 post boxes. The number of ways in which these letters can be posted is -

The number of ways in which 10 letters can be posted in 5 letter boxes is

The number of ways in which 5 letters can be posted in 10 letter boxes is

The number of ways in which 10 letters can be posted in five letter boxes is

The number of ways in which we can post 5 letters in 10 letter boxes is

The number of ways in which one can post 4 letters in 5 letter boxes, is

The number of ways in which one can post 4 letters in 5 letter boxes, is

There are 4 letters and 5 boxes in a row. Number of ways of posting these letters if all the letters are not posted in the same box is

There are 4 letters and 5 boxes in a row. Number of ways of posting these letters if all the letters are not posted in the same box is

There are 4 letters and 5 boxes in a row. Number A of ways of posting these letters if all the letters are not posted in the same box is