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Thread: can you add?

  1. #1
    Platinum Lounger
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    can you add?

    Take 1,000 and add 40 to it.
    Now add another 1,000.
    Now add 30.
    Add another 1,000.
    Now add 20.
    Now add another 1,000.
    Now add 10.

    What is the total? Once you've added it all up in your head, look at the hint below.

    <span style="background-color: #FFFF00; color: #000000; font-weight: bold"><font color=yellow>hint: <big><big><big>NO!</big></big></big> it isn't 5,000</font color=yellow></span hi>

    Then, check it with your calculator if you must....
    Cheers, Claude.

  2. #2
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    Re: can you add?

    Very nice, I nearly got it wrong.

    SturatR

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    Re: can you add?

    <span style="background-color: #FFFF00; color: #000000; font-weight: bold"><font color=yellow>I automatically applied what I used to teach when I was a mathematics teacher - first add the thousands, and then the tens. Less chance of confusion then...</font color=yellow></span hi>

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    Re: can you add?

    I remember this object lesson from school, but the example used was for improper fractions. I can't recall the term for numbers like 17 1/3, but there were a bunch of these to add up, with rather large whole number bits and a variety of denominators.
    <span style="background-color: #FFFF00; color: #000000; font-weight: bold"><font color=yellow>Most students were so engrossed in the current topic, of converting everything to improper fractions, then converting them all to the LCD, that they forgot the obvious - to add all the integers first. It was a good and laborious object lesson... I still remember it.</font color=yellow></span hi>

    The term "object lesson" was, much later, desecrated by my C++ lecturer, who claimed that all his lectures were "object lessons" <img src=/S/grin.gif border=0 alt=grin width=15 height=15>.

    Alan

  5. #5
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    Re: can you add?

    I have a gloriuos mental image of your lecturer desecrating an object lesson.
    I suspect he/she may have deprecated it too.

    StuartR

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    Re: can you add?

    Ok, I'm a complete math geek-WHY DOES IT NOT ADD UP TO 5000 ON THE CALCULATOR???????? If I go number by number in my head I come up with 5,000, which I'm sure many other people do as well <img src=/S/bwaaah.gif border=0 alt=bwaaah width=123 height=15>

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    Re: can you add?

    <span style="background-color: #FFFF00; color: #000000; font-weight: bold"><font color=yellow>Straightforward:
    1,000 + 40 = 1,040
    1,040 + 1,000 = 2,040
    2,040 + 30 = 2,070
    2,070 + 1,000 = 3,070
    3,070 + 20 = 3,090
    3,090 + 1,000 = 4,090 (not 4,990!)
    4,090 + 10 = 4,100

    The "trick" of this puzzle is that you'll easily lose track of the hundreds in the intermediate answers. At the last step, when you add 10, it is easy to become confused by the 9 in the intermediate answer, and your preference for "neat" answers pushes you almost automatically towards 5,000.

    Smarter: take a look at the entire instruction.
    You have to add 1,000 four times, that makes 4,000.
    And you have to add 40, 30, 20 and 10. Thers add up to 100.
    So the end result is 4,000 + 100 = 4,100.</font color=yellow></span hi>

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