I (imaginary)

i is a number that is part of the Complex Number and Imaginary number sets. It is equal to the square root of -1, meaning that -1 = i^2.

i^x
If the remainder when x / 4 is 0, then i^x is equal to 1. If the remainder is 1, then i^x = i. If the remainder is 2, i^x = -1. Otherwise, i^x = 1.