How many numbers of four digits can be formed with the digits `1,2,3,4,5` if the digits can be repeated in the same number?

Explanation

To solve the problem of how many four-digit numbers can be formed using the digits `1, 2, 3, 4, 5` with repetition allowed, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Digits Available**: The digits we can use are `1, 2, 3, 4, 5`. This gives us a total of 5 different digits.

2. **Determine the Number of Positions**: We need to form a four-digit number. This means we have 4 positions to fill (thousands, hundreds, tens, and units).

...