1796 Innumeracy

There was talk recently that we spend too much time worrying about our kid's math and science scores. After all, one group maintained, when do we really need calculus? And who cares if x and y equals z? Everyday life is more about negotiating with people and finding ways to earn money to pay for cool stuff like smartphones.
The argument has a certain appeal. Especially to those who remember suffering through Mr. Poindexter's algebra class right before lunch break. Growling stomachs amplified by wooden elbow desks seemed to proclaim, "X schmex, let's eat..."
Well here's why you need math. Some stores are trying to screw you. A recent study by the University of Minnesota showed that a store will sell 73% more hand lotion when they offer 50% more in quantity than when they offer a discount of 35%. The discount of 35% is actually a better deal. Researchers call it a numerical blind spot.
If an item is a dollar, 33% extra is not as good a deal as 33% off. One gets you a cost of 75 cents and the other a cost of 67 cents for the base unit.
The researchers call this "innumeracy." Kind of a math version of illiteracy. People who can't comprehend numbers. Stores do this on purpose and you end up holding the fractionally shorter end of the stick.
They also double discount. Because people think if it's 20% off and then an additional 25% that the whole thing is 45% off. Nope. It's actually just 40%. Because the second discount isn't on the whole amount.
But us inummerate types jump to the easier percentage-free math. My advice: Use that smartphone. Admit it. It is smarter than you. Especially if you can get a "fraction app" for 50% off.
America, ya gotta love it.