Answer:
-i
Step-by-step explanation:
i^0=1
i^1=i
i^2=-1
i^3=-i
i^4=1
This repeats so we want to see how many 4 factors of i there is in i^(23) which is 5 with a remainder of 3.
So i^(23)=i^3=-i.
i^(23)=i^(5*4+3)=(i^4)^5 * (i^3)=(1)^5 * (-i)=1(-i)=-i.