My formula looks like this (it would be in column C):

=B2&ROUND((RANDBETWEEN(111,999)),0)

This produces something like 01845.

I have a large list of people and I am trying to give them random ID numbers but still be able to organize them a bit (01,02, etc.)

Two questions:

Is there a way to assure that no two numbers will be the same?

Is there a way to add a row without changing the rest of the random numbers? I tried to copy the list of ID numbers and paste them as values and sort them to see if there were any repeats, but this actually gave me different numbers and didn't sort them.

Thanks in advance.