Skills not practiced are lost.
I am not sure that most retail associates would be able to calculate the correct change for a $37.63 charge if the customer presented a $100 bill. Retail clerks rely on the cash register to calculate the sales tax and change that should be returned to the customer. Some registers even suggest alternative combinations of bills and coins to hand to the customer so that the proper change is delivered.
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As a child, I was taught to accurately compute my sales totals, estimate the sales tax, and determine the anticipated change that I would receive for each purchase that I made. I was even taught to do these calculations in my head, without the help of a pencil and paper, let alone a calculator or automatic cash register—not that I would have been able to bring a cash register along in my pocket! To this day, I can quickly do a fast estimation of arithmetic, especially summations. This is a skill that serves me well as I move through the checkout line at the grocery store.
I find it difficult to believe that the proliferation of electronic calculators, spreadsheet applications, and yes, self-totaling cash registers has not had a deleterious effect on the general population’s skills at arithmetic. Skills, once learned but rarely practiced, are lost. Skills never learned are, by definition, lost to the user.
The general population, by all accounts, feels no need to learn, let alone practice, arithmetic, in its daily activities. Prove this to yourself by mentally estimating the cost of a fuel for an 850 mile road trip in a vehicle that yields 28 miles per gallon of gasoline at a cost of $3.05 per gallon. Even a quick estimate, without minor rounding of $1.00 per 10 miles, times 85 (or $0.10 per mile times 850) equals a rough estimate of $85 in gasoline cost (close to the actual cost of $92.59).
My mother, who was graduated from only high school just after World War II and had no further academic training amazed me recently during a phone call by arguing that airline fares would cost less than the cost of fuel and lodging should she and Dad come for a visit. It is just this type of numeracy that is lost to the current generation of Americans. Why have we lost this skill?
Without a calculator, most of us are innumerate. As helpful as a calculator or spreadsheet is to use—and I own at least a dozen calculators of various sizes—I rue our loss of the skills that were once considered academic de rigueur.