The majority of people who learn mathematics in school (K-12) will only use a very small subset of what they learn. This makes perfect sense; if you’re not a mathematician or engineer, when are you going to use trigonometry or solve systems of equations? We carry our arithmetic skills (and some algebra skills) into the real world, and that’s that.

A large amount of the mathematics learned in schools really just provides a foundation of knowledge for mathematicians and engineers, and is discarded by the average person. We could do away with that portion and teach it to the engineers/mathematicians in college. There are problems with this, related to time spent in school and the interest that people may not show until the more advanced stuff, but they’re not the point of this article.

Despite all this extra math, I think there’s one really important real-life math skill that’s lacking or missing from grade school mathematics: estimation.

The ability to estimate well (and recognize when someone else’s estimation is good or bad) is a skill that’s critical if you want to avoid getting screwed over. In no place is this better evidenced than the gas tax holiday.

Some extremely quick estimation can be done to show how stupid this idea is:

The average commute is about 28 miles roundtrip (that’s an overestimation, which is another important tool in proving a point). 28 miles a day times 5 days a week is about 150 miles a week (estimate). 150 miles a week times 13 weeks in a summer is 1950 miles.

The average gas mileage on cars in the US was about 24 in 2004 (estimate). 1950 miles / 24 miles per gallon is about the same as 2000 miles / 25 miles per gallon, which comes out to 80 gallons.

The gas tax holiday would cut 20 cents off the gas price. This means, in saving 20 cents on each of those 80 gallons, we’re saving 80 * 0.20, or about 80 * 0.25 (which means 1/4 of 80). Yes, that means that the average American would save an entire $20, or half a meal at Friendly’s, with this gas tax holiday.

Unfortunately, most people have lost me before the end of the first paragraph. I didn’t do any difficult math; you probably learned all that stuff before 9th grade. But people balk as soon as you start multiplying and dividing quickly, because they never learned how to estimate. They never learned that it’s ok to turn 1950 into 2000 as long as you aren’t filling out a tax report or talking about Frank Sinatra.

I think that this skill should be emphasized much more in school. It’s extremely valuable, allowing you to make points quickly, parse complicated statistics in a meaningful manner, and just be more competent at life in general.