Question

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

Answer 1

Given: There are $7$ letters & $4$ letter boxes.

Each letter can be posted in any one of the $4$ letter boxes.

Number of ways of posting one letter $=4$

$\therefore$ Required number of ways of posting the $7$ letters

$=4\times 4\times 4\times 4\times 4\times 4\times 4$
$=4^7$

$\left[\begin{array}{ccc}Byusingthefundamentalprinciple& & \\ ofMultiplication& & \end{array}\right]$

Hence, Required number of ways are $4^7$.