Question

How many $3$ digit numbers can we make using the digits $4,5,7$ and $9$ and where repetition is allowed?

• A. $3^4$
• B. $3^3$
• C. $4^4$
• D. $12$
• E. $4^3$

Answer 1

The correct option is E $4^3$

We have four digits.

The numbers we need to make have $3$ digits.

There are $4$ choices for the first digit, $4$ choices for the second digit and $4$ choices for the third digit since repetition is allowed.

Hence, the total number of $3$ digit numbers that can be made is equal to:

$4\times 4\times 4=4^3$

Hence, option E is correct.