In reply to John Lay.

The easiest way to test the uniformity property of a random number generator (RNG) is to generate, say 75,0000 (=750*100) numbers and then check that each number appears approximately 100 times. You should observe that most numbers appear between 80 and 120 times. The "formula" is the expected value and confidence interval for a binomial distribution, which might be more complicated than you are looking for.