Here is my dilema...

I have a huge list of data, which consists of different products and details. Each product originiates from a specific/different factory. There are many products produced at a factory, (there are a total of 7 factories). However, the name of the factory is not included in the spreadsheet. What would be the best way for adding the factory name in a new column? I thought about setting up an if-then, but there are about 200 products.... how could I write a marco that I could run that would do this? Thanks for your help!