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Thread: fractuin

  1. #1
    Junior Member
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    fractuin

    fractuin = fraction
    What the reason that multiplication of fractions is:
    Suppse:
    a/b, c/d are fraction.
    The product:
    (a / b) * (c / d) = ac / bd
    Last edited by policer; Feb 17th 2018 at 09:13 AM.
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  2. #2
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    Re: fractuin

    The "reason" is simply that it's the correct way!

    Try it yourself...use actual fractions...

    Try using google...here's a site:
    https://www.mathsisfun.com/fractions...plication.html
    Last edited by DenisB; Feb 17th 2018 at 01:17 PM.
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  3. #3
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    Re: fractuin

    One way to look at this is that the denominators of fractions are "units".

    If you have 2/3 you have two of these things we call "thirds"- in the same way that is you have "2 meters" you have two of these things we call "meters". Just as if we have a rectangle with width 3 meters and height 20 cm then the rectangle has area 60 "cm-meters" which we would probably convert to either 6000 cm^2 or 0.6 m^2, that is, we multiply the numbers and multiply the units, so 2 thirds time 5 sevenths is 10 "thirds-sevenths" which we would call 10 "twentyfirsts" or 10/21.
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  4. #4
    SGS
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    Re: fractuin

    You can work it out this way ...

    a/b * c/d =answer
    Multiply both sides by b
    a * c/d =b * answer
    Multiply both sides by d
    a * c = b * d * answer
    Divide both sides by a
    c = (b * d) / a * answer
    Divide both sides by c
    1 = (b * d) / (a * c) * answer
    Multiply both sides by (a * c)
    (a * c) = (b * d) * answer
    Divide both sides by (b * d)
    (a * c)/(b * d) = answer
    or....
    answer = (a * c)/(b * d)
    Substituting a/b * c/d for answer from a/b * c/d =answer
    a/b * c/d = (a * c)/(b * d)

    Steve
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