There's a very practical skill that doesn't appear to be taught in school. Someone, somewhere along the line needs to teach how to make back of the envelope estimates of answers to problems.
You should be able to leverage what you already know and get within an order of magnitude of the correct answer.
Ideally this would be something you could teach right after multiplication and division in grade school, then keep repeating through the rest of education.
Teaching it at University is better than never.
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Example: One day on the way home from work, passing a large Digital Billboard in Chicago, my friend wondered how much an Ad on one of them would cost. I did this math:
Estimate the size of the billboard... 10x4 meters
It has to be as bright as the sun to be seen during the day, which is 1000 watts/meter^2
Power for the sign 40,000 watts
Losses for electronics, etc. 50%
Total power 40kw / 0.5 --> 80kw
Cost per kwh - $0.10
Cost per hour to run the sign $8.00
Cost of ownership factor x2
Cost of profit for owner x2
Cost per hour to rent (bulk) $32
Hours/month 730 (round up to 1000)
Cost per month $32,000 - retail
Fact - 6 to 8 ads usually rotate on a sign, costs are $1200 to $15,000 per month depending on site and market. Thus the revenue from a board ranges from $7200 to $120,000 per month.
It turned out that my estimate was in the ballpark. Everyone should be able to do something like that by the time they get to University.