# By what factor do winning chances increase based on total value?

Say I am entering 24/7 in endless sweepstakes, contests, giveaways, drawings, etc.

Assuming each one I enter has no less than 1 in 1,000 chances, but no more than 1 in 1 million (and I enter at least 500), what is the minimum accountable factor of chances and the maximum of me winning anything?

In short, as a simple example, say I enter 20 contests, and each one has a 1 in 10,000 chance of winning. What are my chances of winning anything? Just divide 10,000 by 20?

Sorry if it's a dumb question.

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chance of winning is $1-\left(\frac{n-1}{n}\right)^e$ if you enter $e$ contests with a $1$ in $n$ chance of winning. –  ruler501 Apr 4 '14 at 18:21