If you're dealing with several fractions and you want to know which one is greatest and which one is smallest, start by putting them in a column. Then find the least common denominator. Let's use these fractions:
The least common denominator for these fractions is 18. Set three fractions with 18 in the denominator in a column to the right. Now find the greatest common factor for each fraction. For 
, the greatest common factor is 6. Use the greatest common factor to make the fraction of one.
Multiply each fraction by the fraction of one to get the fraction with the common denominator. The greatest fraction is 
. So 
is the greatest fraction we started with. The smallest fraction is 
, so 
is the smallest fraction we started with.
Try this again with the following fractions:
Which one is the greatest fraction? You might be able to estimate, but let's work it out to be exact. The least common denominator is 20.
The greatest fraction is 
, so 
is the greatest fraction we started with. The smallest fraction is 
, so 
is the smallest fraction we started with.
