i represents the imaginary number, the square root of negative one.
i to the power of 45 is simple. You can find charts of the value of each power of i online. Otherwise you can use a calculator or go through each power yourself. Here:
Now, I might be assuming a bit much by assuming you had a typo in the question, where you meant i^45 instead of ii^45, but of course to be sure, Ill solve that as well.