Look at the fast one they’re trying to pull with my favorite cereal. In nearly every situation, stores incentivize you to buy more product by giving you a discount for getting larger quantities. Super-size meals and Costco are good examples. But every once in a while, they count on your being overly inured to that and innumerate.
The small version is $2.99 for 12 ounces. The big box is $4.99. $4.99 is two thirds more price, so they should give you two thirds more food, or 20 ounces. But they only give you 18.8 ounces. You get ripped off by buying the bigger box!!