Question

In how many ways can 7 letters posted in 4 letter boxes?

Answer 1

Total number of letters = 7
$\therefore$ Total number of letter boxes = 4
$\therefore$ Total number of ways in which 7 letters be posted in 4 letter boxes
=$4\times 4\times 4\times 4\times 4\times 4\times 4=4^7$