As The Atlantic explains, shoppers are pretty bad at math.

The [X amount] extra!

is a common tactic used to put a number in our minds.

The problem is, were not great at converting unit prices on the fly.

The first deal offers 33% extra coffee.

The second takes 33% off the regular price.

Whats the better deal?

And youd be wrong.

Of course, stores dont tend to offer both on the same product.

Either youll see a 33% off discount,or33% extra for free.

However, competing products can.

Unless the bigger box is bigger by a significant amount.

However, it might not actually save you money, unless youve done the math.

The 11 Ways That Consumers Are Hopeless at Math| The Atlantic

Photo byMike Mozart.