Because repetitions are not allowed, there are 5 possibilities for the first digit, 4 for the second digit, and 3 for the third digit. Thus, there are 5 × 4 × 3 = 60 possible three-digit numbers that meet these requirements.
Now that repetitions are allowed, the possibilities are expanded. There will be 5 possibilities for each digit: 5 × 5 × 5 = 125 possible three-digit numbers will meet these requirements.