1. According to the results of a study published in the journal Quantitative Marketing and Economics, a buyer is more likely to buy a dress for $49 than for $44. In the example described, an increase in the price led to a 30% increase in sales.

2. If you see an inscription that says about some fantastic sale, be prepared that the stated discount will be provided for the most useless product that you don't need at all. Maybe you'll even find it —

however, already loaded with other supposedly profitable purchases.

3. Alas, shops are far from altruism. The gift is attached to another product, which price already includes the cost of both items.