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Fractions Review (page 3 of 5)

Sections: Reducing fractions, Mixed numbers and improper fractions, Multiplying and dividing fractions, Adding and subtracting fractions, Adding polynomial fractions

Multiplying fractions is easy: you multiply the top numbers and multiply the bottom numbers. For instance:

    ( 2/3 )( 4/15 ) = ( 2·4 ) / ( 3·15 ) = 8/45

When possible, you reduce. In this case, however, nothing reduces, because 8 and 45 have no factors in common. If you're not sure, you can always factor:

    8/45 = ( 2·2·2 ) / ( 3·3·5 )

Nothing cancels.   Copyright © Elizabeth Stapel 2006-2008 All Rights Reserved

Often, though, something will cancel:

  • Simplify (4/9) * (49/6) * (27/28)

    ( 4/9 )( 49/6 )( 27/8 ) = 7/2

Dividing fractions is just about as easy; there's just one extra step. When you divide by a fraction, the first thing you do is "flip-n-multiply". That is, you take the second fraction, flip it upside-down, and multiply it by the first fraction. For instance:

  • Simplify (3/5) / (9/4)

    (3/5) / (9/4) = (4/15)

  • Simplify (5/6) / 5

    (5/6) / 5 = (1/6)

  • Simplify (4 + 3/8) / (2 + 5/6)

    (4 + 3/8) / (2 + 5/6) = 1 + 37/68
     

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Cite this article as:

Stapel, Elizabeth. "Fractions Review." Purplemath. Available from
    http://www.purplemath.com/modules/fraction3.htm. Accessed
 

 

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