Even a few billion trials wouldn't produce more than the tiniest
fraction of the possible values that *XL* can produce between 1E-307 and
0.999999999999999 (plus zero), so I'm not sure that extrapolating from
experience is a reliable guide...

That doesn't mean that the RAND() function can produce all of those
values, of course. I've never seen any documentation of the exact
algorithm (and ever were I to see it, I tend to doubt that I could prove
whether it was inclusive of zero or not).

In article ,
Brakeshoe wrote:

I am trying to match a clients spreadsheet where they are using RAND() to
generate values for the cumulative inverse standard normal distribution.
According to Excel's built in documentation RAND returns values greater than
or equal to zero and less than one. If this was true I believe I should
eventually see a random number equal to zero be returned. If that happened
then the function NORMSINV(0) would return a value of #NUM!. This has never
happened after many millions of trials. This leads me to believe that RAND is
actually returning values between 0 and 1. Has anyone seen an Excel
documentation that confirms this is the case?