All of this i can't divide big numbers and it say for each problem approximate an answer and then do the division. round answers to the nearest whole number?

As a manufacturer of golf equipment, the spalding corporation wants to estimate the proportion of golfers who are left-handed. how many golfers must be surveyed if we want 99% confidence that the sample proportion has a margin of error of 0.025? assume that a previous study suggests that 20% of golfers are left-handed.