The E is the desired margin of error. N zcsE2. You should only use this if circumstances prevent you from determining an appropriate standard of deviation andor confidence level thereby preventing you from determining your z-score as well.
In this formula z is the z value obtained from the Z distribution table.
The z-score is the number of standard deviations a given proportion is away from the mean. MOE 0977 31623 100 3089. S is the population standard deviation of the data set. Sample Size N 1 Ne 2 N population size.