How do I solve this problem regarding divisibility from my Math Challenge class?

Question

What remainder does the number 123456789 leave after division by 8? Is there a trick to solving this?

Answer 1

You'll get a remainder of 5... you can use the divisibility rule for 8 to do this even if it won't fit in your calculator.

The divisibility rule for 8 is that a number is divisible by 8 if the last FOUR digits are divisible by 8. If you divide the last four digits by 8 and get a remainder (in this case, 5), this is the same remainder you will get for the entire number.

--Louise