Hi all

I am entering some voucher numbers into a cell and wish to copy it down to
autocomplete the rest, however, I can't seem to get it to work. The numbers
I have entered a-

100-199
200-299

so I was hoping I could drag it down to enter 300-399, 400-499 and so on but
it doesn't seem to understand what I am trying to do.

Any ideas how I can solve this?

Thank you
Louise