In z5,+,the unit element is 0, and the inverse element of 2 is 3, so -3 power of 2 = 3 power of the inverse element of 2 = 3 power of 3 =(3+3+3) divided by the remainder of 5 =4.

Or -3 power of 2 = reciprocal of 3 power of 2 = reciprocal of 65438 +0 =4.

The method in < z3,+> is the same, except that the reciprocal of 2 is 1, the cubic of 2 = the cubic of1= (1+ 1) divided by the remainder of 3 =0.