What are four different digits that have the mean of five?

To find four different digits that have a mean of five, their total sum must be 20 (since the mean is the sum divided by the number of values). One possible combination is 2, 4, 5, and 9, as 2 + 4 + 5 + 9 = 20. Other combinations could include 1, 6, 7, and 6 or 0, 5, 8, and 7, but since digits must be different, 0, 5, 6, and 9 would be another valid set.