Odds of winning the lottery if I buy 10,000,000 tickets In a lottery whose numbers consist of 7 digits, 0–9, there are $10^7$ possible winning combinations. What would be the odds of winning if I purchase 10,000,000 "quick pick" tickets, where the numbers are randomly picked on my behalf?
 A: Well, the probability of one of the tickets not being the winning combination is $$\frac{10^7-1}{10^7}.$$ If all the tickets were truly randomly chosen (so that one or more tickets may be identical), then the probability that none of them is the winning ticket is $$\left(\frac{10^7-1}{10^7}\right)^{10^7}\approx0.367879.$$ Can you get the rest of the way?
A: Let $N=10^7$. I will assume that the "quick pick" selections may repeat. The probability that one particular ticket is a non-winning one is $1-\frac{1}{N}$, so the probability they are all non-winning is $\left(1-\frac{1}{N}\right)^N$. Thus the probability of at least one win is $1-\left(1-\frac{1}{N}\right)^N$. 
The number $\left(1-\frac{1}{N}\right)^N$ is very close to $\frac{1}{e}$, where $e$ is the base for the natural logarithms. This is because $e^x = \lim_{n\to\infty}\left( 1 + \frac x n \right)^n$ and $\frac 1 e = e^{-1}$.
Numerically, the probability of at least one winning ticket is approximately $0.63212$.
You may get more than one winning ticket, in which case you have the pleasure of sharing the grand prize with yourself, and perhaps others. On average, the more you play, the more you lose.
