Let's say I played 500 hands in poker and earned 345 units ( dollars not, important for calculation). So on long term I'm earning 345/500 = 0.69 * 100 = 69 every 100 hand session. But 500 hands is just to small sample. I could easly loose 200 dollars in next 500 hands( -40 dollars every 100 hand session). So in 1000 hands I've played my neto won would be 345-200 = 145 / 1000 = 0.145 * 100 = +14.5. What minumum sample of hands would be necessary to find out how much I'am wining/loosing every 100 hand session with error of lets say of +-5%. I know if I play 100,000 hands and my wining rate is 9 dollars every 100 hand sesion I will have approximately same result if I played 200,000 hands. How to calculate those stuff?