For which other positive integers a, less than 11, will the number (a^n) + (a^(n+1)) + (a^(n+2)) + (a^(n+3)) + (a^(n+4)) always be divisible by 11? For example, (4^n) + (4^(n+1)) + (4^(n+2)) + (4^(n+3)) + (4^(n+4)) is always divisible by 11, no matter what number n is equal to.

Please help and answer with the entire explanation.

I am struggling so hard... :(

​