I'm wanting to use the =RANDBETWEEN Function for a growing price list (updated monthly) where I'm wanting to generating my own random codes, but I don't want any duplicates.

Example. I have a price list with 1000 lines. I want to generate a number from 100000 to 999999 that is random without repeating. I'm not sure how good the =RANDBETWEEN function works for this...

The next problem is, this price list will keep expanding. Meaning next month I have to add 1000 more codes that I also want to generate Random numbers from 100000 to 999999 that will be added to the list of random generated numbers I created last month, without creating duplicate from the numbers created last year.

Is this possible?

Thanks,