Quote:
Originally Posted by retina
Isn't there a factor missing: Namely the probability of a number being prime.
Probability per day = (tests per day)*(probability of error)/250,000 * probability of being prime

What is the role of the magic number "1/250000"?
Also, it is not "Probability per day", it is "Expected primes per day" (as in, with really large values, the result can easily be > 1)