You can read about it in the wikipedia here. According to one study in Britain more than 80 per cent of all promotional activity in retail was a variation of this. Not surprising as it is probably the most effective and well-liked form of marketing used today in retail. Its easy to set up with our point-of-sale system and we can accompany its many varieties, e.g. buy 8 coffees and get one free. Another variation we can do is buy one, and you will get 50% off the second. Sometimes a a different product is is used completely e.g. buy a sandwich and chip and get a drink free.
Our point-of-sale system does all this very well. To set this up all you need to do is follow the red arrows in the image below.