Simple Calculations

I’ve always liked numbers. That’s why I was so disappointed when I got into the first grade and found they were not teaching arithmetic. In my school in my time, arithmetic didn’t happen until the second grade. Today not knowing your numbers and being able to do a little adding and subtracting when you start kindergarten means you missed out on the preschool or Head Start program that would have properly prepared you.

In any case I learned some arithmetic in the second grade.  The third grade had two classes taught by Mrs. Ener and Mrs. Bugbee. You were lucky if you got into Bigbee’s class because she was the “easy one.” But I got Mrs. Ener, who required every student to pick a day to stay after school, stand next to her at her desk and give the answers to the 100 addition facts on a book as she pointed to each one. If you missed a single one or took too long, you were out.  Come back and try again.  It was considerable pressure for an eight-year-old.  Besides, you had to give up your free time, staying after school and waiting in line behind others, giving you plenty of time to psyche yourself out.  After you successfully ran that gauntlet three times earning three stars on the bulletin board, the same routine followed with subtraction, multiplication and division – perfectly three times each.

As nerve-racking as it was, perhaps everyone needs a Mrs. Ener somewhere along the academic path, because so many problems we run into in daily life come down to simple arithmetic. One example was when I handed a cashier $22.59 to pay a $7.59 bill.  She thought the $20 bill was a $5 bill and rang up $7.59 on the cash register, which told her not to give me any change.  A co-worker pointed out that I had given her a twenty and panic set in. How much change should I get?  How about 20 – 5 dollars?  (The matter was resolved after a couple of wrong guesses.)

Here is another I came across in a magazine ad for a wristwatch selling for only $29 plus shipping and handling. The copy read: “Precision timing that’s accurate to four seconds a day – that’s more precise than a 27-jewel automatic priced at over $6000.”  That sure sounds impressive – until you do the numbers.

Four seconds a day means 4x30 seconds per month (approximately) = 120 seconds or 2 minutes. So far the calculations are easy. Two minutes a month will not make you late for very many appointments, although it might make catching a train in Tokyo a little iffy. But 2 minutes a month times 12 months (another easy, do-it-in-your-head calculation) comes out to 24 minutes a year – almost half an hour! Is that precision?

When we change time twice a year (from EST to EDT and back) and I have to reset the clock in my car, I just push the button to adjust the hours. I don’t expect the minutes to be about 12 minutes off. I expect the minutes to be pretty darn close, and they are! Does that mean the clock in my car is enormously more accurate than a $6000 wristwatch?  Maybe so, but it’s what I expect.

Doing simple calculations is a small part of critical thinking. Do the advertisers think that most people will breeze right by without thinking, accept their assurance of world-class accuracy, and  send in their $29 plus S&H? Apparently so. This great deal is limited to the first 1900 that call with the special offer code – better hurry (and not think about it too much)!

The simple-calculations habit can save a lot more than $30 over the course of a lifetime!