populating excel columns with incrementing information

microsoft excel - there must be a way of doing this but I have no idea where to start so if anyone can help please?
I want to create a column that will look something like this:
[PACS_001]
[PACS_002]
[PACS_003]
...
[PACS_300]

there must be some way of automating the population of this column - and I have another 3 or 4 columns that will need something similar - so a formula that can do this work would be VERY useful to me