Let's raise i to various powers starting with 0,1,2,3...
i^0 = 1
i^1 = i
i^2 = ( sqrt(-1) )^2 = -1
i^3 = i^2*i = -1*i = -i
i^4 = (i^2)^2 = (-1)^2 = 1
i^5 = i^4*i = 1*i = i
i^6 = i^5*i = i*i = i^2 = -1
We see that the pattern repeats itself after 4 iterations. The four items to memorize are
i^0 = 1
i^1 = i
i^2 = -1
i^3 = -i
It bounces back and forth between 1 and i, alternating in sign as well. This could be one way to memorize the pattern.
To figure out something like i^25, we simply divide the exponent 25 over 4 to get the remainder. In this case, the remainder of 25/4 is 1 since 24/4 = 6, and 25 is one higher than 24.
This means i^25 = i^1 = i
Likewise,
i^5689 = i^1 = i
because 5689/4 = 1422 remainder 1. The quotient doesn't play a role at all so you can ignore it entirely
To find how much Henry can expect to receive from Social Security on a monthly basis, we first need to find how much he cant expect to receive from social security per year.
We know form our problem that Henry averaged an annual salary of $45,620, so to find how much can Henry expect to receive from Social Security per year, we just need to find the 42% of $45,620.
To find the 42% of $45,620, we are going to convert 42% to a decimal by dividing it by 100%, and then we are going to multiply the resulting decimal by $45,620:

Social security annual payment = (0.42)($45,620) = $19,160.40
Since there are 12 month in a year, we just need to divided the social security annual payment by 12 to find how much he can expect to receive each month.
Social security monthly payment =
= $1.596.70
We can conclude that Henry can expect to receive $1.596.70 monthly from Social Security.