Answer
d = 4
Work Step by Step
Divisibility Rules tell us that for a number to be divisible by 8, its last three digits must form a number that is divisible by 8.
In our case: 8|88,888,82d. Our last three digits are 82d, with d being an unknown value we need to find.
If we substitute each number 0 through 9 into 82d for d and check to see if the number formed is divisible by 8, we find that only 824 is divisible by 8. Therefore, d = 4.