Pursuant to the first problem in this series, this one involves checking for divisibility by 8.

Write a function to determine if a number is divisible by 8. This can be done by the following method:

1. Check the last three digits for divisibility by eight. If that portion of the number is divisible by eight, then so is the original number. That three-digit number can be further reduced by summing four times the hundreds digit, two times the tens digit, and the ones digit. As with methods for other numbers, this factor/sum step can be applied recursively until a single-digit number results.

Previous problem: divisible by 7. Next problem: divisible by 9.