Question

In how many ways can 5 letters be posted in 4 letter-boxes?

• A. 512
• B. 1024
• C. 625
• D. 20

Answer 1

The correct option is B 1024

First letter can be posted in 4 letter-boxes in 4 ways.
Similarly, second letter can be posted in 4 letter-boxes in 4 ways and so on.
Hence all the 5 letters can be posted in
$=4\times 4\times 4\times 4\times 4=1024$