Question

A four-digit number is to be made using the digits 1, 3, 5, and 8. How many numbers can be made if repeated digits are allowed?

Answer 1

We want to make a four digit number using numbers 1, 3, 5 and 8 and allowing repetition.

Therefore, there is four possibilities each for the units, tens houndreds and thousands.

Then, the total number of possibilities is:

$4\cdot4\cdot4\cdot4=4^4=256$