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

5 letters can be posted into 3 letter boxes in:

5 letters can be posted into 3 letter boxes in:

Find the number of ways in which 5 letters can be posted in 3 post boxes if any number of letters can be posted in a post box.

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 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