Tuesday, April 19, 2011

Lacking Numerical Sense

We math teachers somewhere in the past decade or two have failed at stressing the value of the decimal. The once 14-years-old are now 20-somethings, making up a large percentage of the working force in the service industry. Many of them are in decision-making, managerial positions. These people would swear on their lives that 25 cents is written as 0.25¢! You see signs everywhere stating, “All size drinks for only 0.99¢!” Even if I were to plunk down a shiny new penny and order one large Coke, Suzy behind the counter wouldn’t have the faintest idea where I was coming from. It would only annoy her that I was slowing down the line.

Not all 4’s are created equal. Huh? Let me clarify. A salary of $4,000 is quite different from that of $40,000. Wouldn’t you agree? All because of one seemingly insignificant little dot. So, how can $0.25 = 0.25¢ or 25¢ = 0.25¢ ? It totally baffles me.

Here are other examples I have found in the last eight months.






Don’t despair. There is hope. A nearby grocery store remodeled recently. During their grand reopening, I noticed that in their produce section, all price signs had both a decimal point and a cent sign. How sacrilege! Much to my teenager’s dismay and embarrassment, I took it upon myself to remove all the plastic decimal tiles and neatly placed them in a pile to the side. You will be happy to know ever since that liberating day, this particular grocery store has not made the same erroneous mistake. Somewhere in their security office is probably a picture of me with the caption, “WARNING: Watch out for a crazy woman rearranging store merchandise!”

2 comments:

Brandy King said...

A lot of students struggle to recognize that there is a difference between $0.50 and $0.5 (the answer the calculator gives). They will write $200 instead of $2.00 and argue that it is the same thing. Your pictures could help lead an interesting discussion with your class. What a great way to stress the importance of place value.

Steve Ritter said...

You should try to get 2 of those pencils for a penny - see what they do.

For a particularly sad example of not understanding the importance of decimal points in money, see http://verizonmath.blogspot.com/

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