How to determin if a large exponent is divisible by 9

I have a question and my exam is tommorow.I hope I am posting this in the correct section. I need help please!
The question goes
is the integer 1234^5678 + 5678^1234 divisible by 9?
Now i know that for an integer to be divisible by 9, the sum of the digits must be congruent to 0 modulo 9. However, i do not know how to expand out the large exponents to sum up the digits and the stupid professor does not reply his email! I hope i can get some help here
Many many thanks!

There is a divisibility theorem that states any combination of terms which are divisible by "n" will also be divisible by "n".