[ThrowawayR2]

"We have calculators so arithmetic matters less" you say?

https://en.wikipedia.org/wiki/Third-pound_burger#Marketing_f...

"The results revealed that many participants mistakenly believed that one-third of a pound was smaller than one-fourth (quarter) of a pound. Focus group participants expressed confusion over the price, asking why they should pay the same amount for a "smaller" third-pound burger."

[ryandrake]

I always thought that fast food companies should have used that research to take advantage of the public’s innumeracy and offer a “1/5 pound” burger next to their 1/4 pound burgers, and charge more for it.

[graemep]

I agree with that, but most of those people probably can do arithmetic and were drilled in it at school, but drill to get the right answers does not teach you how to apply it.