Considering there are 10,000 unique combinations of four digits (0000 through 9999), how many random four-digit combinations would I have to go through until I have at least one sample of each possible combination? On average, how many could I expect to match if I generated exactly 10,000 samples. At what point is the probability 99%? This question involves masked social security numbers and how many I would have to go through until there are no longer any unique ones. I just don't have the math chops to figure this out on my own! :)
How many random 4-digit numbers would I have to go through to get every possible combination?
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2Google "coupon-collector-problem" for the first question. – 2017-02-24