Obscure / encrypt an order number as another number: symmetrical, “random” appearance?

Question

Client has an simple increasing order number (1, 2, 3...). He wants end-users to receive an 8- or 9- digit (digits only -- no characters) \"random\" number. Obviously, this

Answer 1

If your Order Id is unique, Simply you can make a prefix and add/mix that prefix with your order Id.

Something like this:

long pre = DateTime.Now.Ticks % 100;
string prefix = pre.ToString();
string number = prefix + YOURID.ToString()