Simplify i^51

Question

Im really not sure what they are saying. i to the 51ith power? Wouldnt it already be simplfied or what. It doesnt make sense to me.

Answer 1

i is sqrt (-1)
i^4 which is equal to (i^2)^2, or any integer power of i^4, is equal to 1

i^51 can be written i^48*i^3 = 1* i^3

Since i^2 = -1, i^3 = -i

So -i is the answer.