Find the number of ways in which one can post 5 letters in 7 letter boxes.
We have to find the possible number of ways in which we can post five letters among seven letter boxes when repetition of distribution of letters is allowed.
We will use the concept of multiplication because there are five sub jobs dependent on each other and are performed one after the other.
The thing that is distributed is considered to have choices, not the things to which we have to give them; it means that in this problem the letters have choices more precisely seven choices are there for each letter and letter boxes won’t choose any because letters have the right to choose.
The number of ways in which we can post letters among seven letter boxes where repetition of distribution is allowed 7 × 7 × 7 × 7 × 7 = 75 = 16807.