Harlan Grove wrote:
There's *NO* chance of duplication using RAND()
alone when only 15 numbers are involved.
[....] The only way you get duplicates from
pseudorandom number generators is by drawing
more deviates than the period of the generator.
The period of Excel's generator is more than
1,000,000, so no duplicates in a range of only
15 cells.

Good point. I thought of that, too. But I try to
not make ass-u-me-tions about algorithms that I have
no control over, and especially about undocumented
features. For example, what if RAND() later can
utilize a hardware RNG, if it is installed?

Don't get wrong: I must admit that your assertion
is quite likely right in the case of generating only
15 RAND() values. I was probably being a little
anal. But I thought the point was important to make
since some people will apply these ideas to very
different circumstances.