Rounding off the dollar - with no sense

THE bill for my car insurance was $203 on the nose. A carpenter friend working on my house charges me a nice tidy sum each week. He rounds it down to the nearest dollar, he says, and I believe him. I am not so sure about my insurance company.

The man who does my taxes also evens off my deductions as well as my final obligation to the IRS. I always mean to ask him to tack 17 cents onto the bottom line so it will look more realistic.

The other day I bought $1.01 worth of junk food at the nearby country store and handed the woman a ten-spot. She returned nine dollars without even asking if I had a penny.

Rounding (up or down) to the nearest dollar is not the greatest evil afoot in the world today. If the practice stopped there, it would be nothing more than a convenient, timesaving accounting procedure.

A prestigious newspaper hereabouts carried a story recently about a state construction project that ''will cost $65 million.'' Not $65,000,00.17 or $64, 999,973.95, but precisely $65 million. Somehow that last abbreviated figure, coupled with the clairvoyant reporter's use of the phrase ''will cost,'' makes the whole scheme appear more reasonable and manageable.

If expenditures come in conveniently manageable decimal units these days, revenues must follow suit, naturally. A news story in another large daily paper stated that a new Lotto game helped to increase my state's income from legalized gambling to a ''new high of $148 million for fiscal 1984.'' You have to give those legalized gamblers credit; they sure know how to bet even numbers. A lottery official said he was hoping for a more ambitious haul - $200 million by 1986. Now you see where newspapers get those cuddly round figures.

But for really big numbers with scads of zeros in tow, you have to look to Washington. The Senate and the House are forever fighting over $4 billion here and $50 billion there. Sometimes Democrats and Republicans get into a tiff over the more than trillion-dollar federal deficit. Written out (which is rarely done), a trillion dollars is $1,000,000,000,000.00. Publications love to explain such indigestible figures this way: ''It ain't chicken feed, but if it were it would feed all the cluckers that have ever lived for a millennium.'' Why not just print the zeros?

Numbers with no pesky odd numerals at their conclusions and no cents tagging along behind have a lulling effect. When condensed into visually pleasing packages they seem innocuous, like the amounts we spend repairing our cars. At the same time, there is an air of unreality about sums like $65 million. Can we really trust people who round money off to the nearest million to get the job done on budget?

The late demagogue, Joe McCarthy, knew what sort of numbers were credible and which weren't. When he announced in 1950 that there were Communists in the federal government, he didn't claim there were 100 or 200. Who would swallow those symmetrical tallies? No, he said there were 205 slippery subversives in Washington, and people believed him. He later adjusted his fabricated list to 57 , an even more plausible combination of digits.

After returning from the country store with my junk food and the penny the cashier disdained, I made some calculations. Let's assume that $10 to that little store is the rough equivalent of a billion dollars to Uncle Sam (please excuse my shameful rounding off); Washington, then, looks as cavalierly on a million bucks as that woman did on her missing penny. That would explain why congressmen are fond of the expression ''a million for your thoughts.''

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