Hey, this ain't the right answer!

 

By Joe Walther

 

My cell phone rang. It was 4 PM on Friday afternoon. “I just paid fifty bucks for a new calculator and it doesn’t work,” she said. “Is there any chance of you taking a look at it before I take it back and raise hell?” I told her that I was headed to Borders Book Store in Stanton, but I’d be…. “Great,” she interrupted, “I’ll meet you there.” The line went dead.

 

            Melissa; that’s who called; teaches junior high—7^th and 8^th grades—in one of the school districts in New Castle County, Delaware. I met her about 15-years ago at a Microsoft Excel workshop. I was conducting and she was one of the most attentive participants I’ve ever had. We’ve been friends ever since. Incredible intelligence aside, she’s a bit impulsive and high-strung, attributes that are handsomely offset by an obvious willingness to give her last dime to a cause if she believes in it.

 

            Twenty minutes later, the two of us were sitting at one of the tables in the bookstore coffee shop; I mean café. At the prices they charge, I think the law requires them to call it a café. Anyway, she handed me the calculator and the accompanying 110-page manual.

 

            I found myself holding a genuine Texas Instruments BA II Plus™. It is one of the best financial calculators on the market. While it does all of the little stuff (add, subtract, multiply, and divide) and some of the routine scientific stuff such as squares, roots, logs, sine, cosine, reciprocals, and a few others, it’s not, strictly speaking, a full-scale scientific calculator. Its strong suit, however, is heavyweight financial calculations.

 

            Since 7^th graders have no real need to know this stuff, at least at this sophisticated level, I wanted to know why she chose a financial calculator. She explained that, for the price, this one seemed like a “kill two birds for the price of one” deal. She thought that she’d be able to do the general arithmetic applications for her students and learn the financial functions for herself. Please note! Melissa does not permit her students to use calculators in her math class. She, however, uses one in grading their assignments.

 

            Ok, this seemed soundly logical, but I wanted to know how she knew that the calculator didn’t work. “I tried one of the problems in our 7^th grade math workbook; I could not get the answer in the back of the book.” Here’s the problem she had entered: 20.513+10.375x2.434. She showed me her work. The calculator answer was 75.181. The textbook’s answer was 45.766. The textbook answer is the correct one, of course.

 

            Most financial calculators—I’ve not found one that does not— employ the Chain system (Chn) for string operations. In other words, the calculator solves strings in the order that the user enters them. In the problem above, the calculator adds 20.513 to 10.375 and then multiplies the sum by 2.434. It’s WRONG and this kind of nonsense is the leading cause of heart attacks in people like me! Well, ok, wild sex orgies are the leading cause, but this is a close second, though!

 

            Oh, and before I forget, if the sex is good, I do not consider a fatal heart attack to be an unreasonable price for me to pay. This assumes, of course, that it occurs at the PROPER time, if you get my drift.

 

            Now, back to the subject at hand. A scientific calculator uses the Algebraic Operating System (AOS). It multiplies 10.375 by 2.434 because multiplication comes before addition and subtraction, and then adds 20.513. This is the CORRECT way to do it. It has always been the correct way to do it because some dude (or maybe a dudette) back in the BC era, determined that there is an absolute mathematical operations hierarchy. If you are unfamiliar with it, I question how you slipped past the 7^th grade.

 

            In fairness to Texas Instruments, financial calculators use Chn for string calculations because financial folks wanted it that way. In the early days before calculators, people had to administer the math hierarchy manually by inserting parentheses to change it. When calculators became dominate, the manufacturers built Chn into the operating systems because the users wanted to continue manually changing the hierarchy.

 

            Melissa didn’t read the first chapter of the 110-page manual. This one explains how the calculator works. But, even if she HAD read it, Texas Instruments does not take the space to explain why financial calculators use Chn. While the manual explains that a user can change from Chn to AOS, it isn’t very explicit. Nor does it explain in any way that the user MUST use parentheses to arrive at a correct answer while in the Chn mode.

 

            I called Texas Instruments and spoke to one of the marketing people there. They understood the nature of my call and acknowledged the validity of my point. They told me that they’d look into the matter. However, it seemed to me that the main thrust of their response was trying to reassure me of their continued commitment to make the operation of their products “intuitively” obvious.

 

            I hate the term, “intuitively obvious.” Not only is it misused, it’s overused to a point of nausea. It is especially handy for making potential opponents—especially those who are conceptually unfamiliar with an idea—feel stupid. I think that we, as a matter of social norm, should electrocute anyone who uses the term. Incidentally, this also applies to all of those who use the terms “fair” and “taxes” in the same sentence. Just as there is no such thing as a universally “fair” tax, nothing is “intuitively obvious” to everyone, not even to the self-professed geniuses of the world. True geniuses never use the term!

 

            To a lucky small child, all of the presents under the Christmas tree makes Santa Claus’s trip from the North Pole “intuitively obvious.” Not so, for the poorest children among us. To an Astrophysicist, the exponent, 1/r², means that if people move twice the distance from the center of the earth, they’ll weigh only a quarter as much as their normal weight. Move ten times the distance and they’ll weigh only one hundredth as much. Not so to your typical politician. Their typical response is, “Huh?”

 

            Melissa is happy with her purchase now that she understands the concept behind Texas Instrument’s use of Chn in its financial calculators and that she can automatically avoid math errors by changing the mode to AOS. At least it seemed “intuitively obvious” to me that she was happy. However, when I told her that she could have purchased the same calculator from Target for half the price she paid at Office Depot, everyone in the Border’s coffee shop, I mean “café”, witnessed her vocal unhappiness.

 

            Why, it was “intuitively obvious” to everyone there, except a State Representative seated next to us. His expression was one of “HUH!” His cluelessness was ‘intuitively obvious” to all us! Or was it? He seemed so preoccupied with a sheet of paper he was holding up. I think it was his son’s semester’s textbook bill!

 

See you next week.

 

Joseph Walther is a freelance writer and publisher of The True Facts. Send your comments. Just click here.