4. A 3-digit combination for a lock is to be randomly generated using rolls of a 6-sided die. The die is rolled once for each number of the combination. How many unique combinations can be generated this way?

1. The die has 6 faces, so each roll can result in one of 6 possible outcomes. 6
2. Since the combination is 3 digits long and each digit is determined by a roll of the die, we multiply the number of outcomes for each digit.
3. The total number of unique combinations is given by: 6 \times 6 \times 6 = 6^3
4. Therefore, the number of unique combinations is: 216

Thus, the answer is 216.