Why Do I Need to Know Math???

I get this question ALL THE TIME from my students..."Why do we need to know math?" 

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Here's what happened today to show why knowing some basic math would be helpful.

We bought an item that was priced $20 and marked 40% off.  The 40% would be taken off at the register.  

When we were checking out, the cashier ripped off the UPC code sticker to scan it due to the size of the item and the lack of having a handheld device.  As she was doing this she said, "Got to be careful that I don't..."  RIIIIIIIPPPPPPPP.  "...do that." 

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She tried a couple different ways to scan it but it didn't work.

So she typed in the price, "$19.99".  I reminded her about the 40% discount.  She called for help. 

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When helped arrived, they came to the conclusion that it should be marked down 40%.  Here's the conversation:

Helper:  "Go ahead and mark it off 40%."
Cashier: "Get a calculator, I don't know what 40% off is."
Brief Pause

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Help: "...Just put $10."
Cashier: {after Helper left} "That's like half off."

Yep, yes it is.  If you know how much we should have paid, thank your math teacher.

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