0.01% of 1000 is 0.1 people, not 1 people, and 82÷1 is 82 and not 8, but you're right that my calculations weren't correct either. You'd get 82 false positives and 0.1 (or 0.0979) true positives, so for every true positive result, you have 820 false positives, not 82300 as I said.