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Thread: TI89 Titanium - Division returning reduced fractions: why?

  1. #1

    TI89 Titanium - Division returning reduced fractions: why?

    For some reason my TI89 Titanium is returning reduced fractions when I try to divide. I've spent an hour and a half combing every page of the manual and still cannot figure out how to get this calculator to DIVIDE two numbers instead of returning reduced fractions. For example I put in 100/16 and I get 25/4 instead of 6.25; I put in 5/7 and I get 5/7 instead of .7143. I'm having a really hard time believing that my 300 page manual doesn't cover this simple issue, but I've looked and looked and i just can't find it. Can anyone out there help me? Thanks.

  2. #2

    Re: TI89 Titanium - Division returning reduced fractions

    OK, I guess I missed a post when I was browsing, but I did find this information in a post:

    "If you type 2,/,3,enter, the ti-89 returns "2/3". If you hit the yellow key with the diamond on it before the enter key, you get .666667 (the decimal approximation)."

    So, now I have a new question: Is it possible to set up this calculator so that you don't have to hit the diamond key to get a decimal answer?

    And one comment: That has got to be the most retarded thing I've ever seen. Why would a company manufacture a calculator to return a reduced fraction using fewer steps than returning a standard decimal answer. I mean, I'm sorry, but when MOST people hit the divide key, I don't think they're looking for a reduced fraction.

  3. #3
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    Re: TI89 Titanium - Division returning reduced fractions

    Quote Originally Posted by AtWitsEnd
    I'm having a really hard time believing that my 300 page manual doesn't cover this simple issue,
    Consider it a good thing you're having a really hard time believing. It shows you're not completely daft.

    Your ti89 is set to exact mode. To force decimal approximation while in exact mode, you only need to insert a single decimal point somewhere within your expression. It's not necessary to put decimal points in every number.

    If you always want decimal results, then change from exact mode to approximate mode. (Press the mode button on your ti89; the screens are self-explanatory.)

    If you always want decimal results, somebody wasted a lot of money.

    You and yours belong to a small group within those doing math, if you and yours believe that everybody wants decimal approximations.

    The Country Doctor

    PS: I don't know what book you're looking at, but my ti89 manual is over 1,000 pages.
    The country doctor

  4. #4
    Elite Member mmm4444bot's Avatar
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    Re: TI89 Titanium - Division returning reduced fractions

    Quote Originally Posted by DrToddMatthews
    ... I don't know what book you're looking at, but my ti89 manual is over 1,000 pages.
    Hello Country Doctor:

    You must be using the electronic version (currently 1008 pages).

    The original printed manual (outdated) is exactly 300 pages.

    Cheers,

    ~ Mark

    PS: I also wonder why the original poster bought a TI-89. It seems like overkill, especially when considering that both PCs and Macs come with built-in scientific calculators.
    "English is the most ambiguous language in the world." ~ Yours Truly, 1969

  5. #5

    Re: TI89 Titanium - Division returning reduced fractions

    Well, you're right, I did buy more calculator than I probably need. I was in a hurry that day and Staples was out of the one I was told to get (for a class), so I got what they had, that I thought would do the job. Perphaps I was reasoning wrong, but I thought if I purchased "up" with features rather than down, I'd have a better chance of the calculator doing what I needed it to.

    It's not that I think everyone, all the time, will want decimals. It just surprised me because I've never really been in a mathematical situation where I needed a calculator to reduce a fraction for me. When I hit the divide button, I expect a calculator to divide, not reduce a fraction. Obviously, I'm nowhere near PhD level math and there's just a lot I don't know about. I guess since the calculator is designed to do far more than I can fathom I just got terribly frustrated not understanding all it's inner workings. I'm now getting the idea that what I was trying to accomplish was probably considered as commonly understood a function as addition and subtraction for those already acquainted with scientific calculators, and, I guess by the time someone gets a ti-89 they surely are already acquainted with scientific calculators. That's why all the manual writers did was show you where you could find the function and didn't explain what it did.

    It's interesting that the 300 page manual is obsolete since they're still packaging it with the calculator. I found the expanded one online.

    So, thanks so much for the explanation of the "mode" button. I can complete my homework now.

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    Re: TI89 Titanium - Division returning reduced fractions: why?

    At first this feature really anoyed me as well, but now, as a calculus student, it has become one of my favorite aspects of the calculator!

  7. #7

    Re: TI89 Titanium - Division returning reduced fractions: wh

    Where did you find the expanded manual?

  8. #8
    Elite Member mmm4444bot's Avatar
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    Quote Originally Posted by RichardTags

    Where did you find the expanded manual?
    Hi Richard:

    I downloaded the PDF user guidebook from the Texas Instrument's web site.

    Their Download Central section offers lots of free stuff, including custom applications for the TI-89 and a flash upgrade for the calculator's operating system to provide bug fixes and additional built-in functions.

    Click HERE to download the user guidebook

    Click HERE to view additional downloads for the TI-89

    Cheers ~ Mark

    "English is the most ambiguous language in the world." ~ Yours Truly, 1969

  9. #9

    Re: TI89 Titanium - Division returning reduced fractions: wh

    Thanks Mark!

    p90x | bowtrol

  10. #10
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    Re: TI89 Titanium - Division returning reduced fractions: wh

    To get the calculator to display decimals instead of fractions, set it on APPROX mode instead of EXACT.

    Go to MODE, scroll down to EXACT/APPROX. You should see three settings: AUTO, EXACT, APPROXIMATE.

    Choose APPROXIMATE to get a decimal display.

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