Easier method to compare fractions

When we want to compare fractions, we often need to know which fraction is larger or smaller.

a/b     >     c/d             OR          a/b      <       c/d    ? 

In order to solve this quickly, we can use cross-multiplication to determine which fraction is larger or smaller.

ad      ?      bc .

If  ad > bc, then the fraction on the left ( that is  a/b ) is larger.  If  ad < bc, then the fraction on the right ( that is  c/d ) is larger.  And if  ad =  bc, then the two fractions are equilavent.

Here is your example :

Which is greater : 7/9  or  5/6 ?

By using cross-multipication, we compare 7×6 and 9×5.

7×6 = 42.

9×5 = 45.

Since 42 < 45,  the fraction on the right is greater.

So the answer is  5/6 .

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Posted on March 13, 2009, in Info Matematik. Bookmark the permalink. Leave a comment.

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