Answer
d = 6
Work Step by Step
Consider 8|76,523,45d when d is equal to 6. For a number to be divisible by 8, its last three digits must make a number divisible by 8.
In our case, the last digit (the ones digit) is unknown. The three digit number we use looks like this: 45d, with d being an unknown value.
If we substitute each number 0 through 9 for d and then check to see if the number is divisible by 8, we find that only 456 is divisible by 8.
