I don't understand how to simply this:
The answer is 4 but I don't know how to work out the solution to get to 4.
Replace 256 with 2^8. Replace the 8th root symbol with ^(1/8) so you have ((2^8)^2)(1/8).
Then use your index law that says (a^m)^n = a^mn and you will have your answer!!
DON'T TOUCH YOUR CALCULATOR!!