Multi-Buy Break-Even

From the book — Chapter 3. A multi-buy only wins on price per item: divide the deal price by the number of items and compare with the single price. (“Buy 2 get 1 free” is deal quantity 3 at the price of 2.) And a discount you won’t use isn’t a saving — if you’ll only use some of them, the offer’s real per-item cost is the deal price spread over what you actually use.