For what purpose?  I'm wondering why it has to be positive and if it really has
to be numeric.  You can have Access generate a random AutoNumber and display it
as a Hexadecimal value.  That gives you a consistent number of characters that
are random and no negative sign (even when the underlying value is negative).

Would that work?

You don't say what the maximum length is, and whether leading zeroes
count toward the digits. Making assumptions, and applying some primary
school maths:

 Largest number 8 digits = 99999999
 Smallest number = 100000

Range = 99999999 - 100000 + 1 = 99900000

So we start with a number n: 0 <= n < 99900000

and then add on the 100000 to get back to the desired range:

 n = Int(CDbl(99900000) * Rnd()) + 100000

Hope that helps

Tim F