Ordering Fractions
Learn to put three or more fractions in order from least to greatest or greatest to least, and to pick the fastest method every time.
Definition
- Ascending order (least to greatest):
- Descending order (greatest to least):
- 1.Same denominator: order the numerators.
- 2.Same numerator: the larger the denominator, the smaller the fraction.
- 3.Common denominator: rewrite every fraction with the least common denominator (LCD), then order the numerators.
- 4.Decimals: divide numerator by denominator and order the decimals.
- 5.Benchmarks , and : sort the fractions into groups first, then order inside each group.
Try it now
Worked Examples
Order from least to greatest: , , ,
Check the denominators
All four fractions are ninths → Same denominator: compare the numerators
Order the numerators
→
Write the fractions in that order
Keep the denominator →
Answer:
Common Mistakes
Ordering unit fractions by their denominators: writing as least to greatest because
Why it's wrong: With the same numerator, a larger denominator means the whole is cut into more, smaller pieces.
Correct: Least to greatest is : the largest denominator gives the smallest fraction.
Comparing only the numerators when the denominators differ, e.g. putting after because
Why it's wrong: Numerators can only be compared directly when the pieces have the same size.
Correct: Rewrite first: , and , so .
Changing only the denominator when rewriting:
Why it's wrong: Multiplying only the denominator makes the pieces smaller without adding more of them, so the value changes.
Correct: Multiply the numerator and the denominator by the same number: .
Mixing up ascending and descending order
Why it's wrong: Students order correctly from least to greatest, but the question asked for greatest to least (or the other way round).
Correct: Underline the words in the question first. Ascending starts with the smallest fraction (), descending starts with the greatest ().
Interactive Visual
Fraction Number Line
Select two fractions to compare them.
Click on the bar to change the fraction
Interactive Sandbox
Expression Calculator
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Practice Problems
18 problemsWhich list shows , , , from least to greatest?
Why It Matters
- Cooking: a recipe lists cup of flour, cup of sugar and cup of milk. Which ingredient do you need most?
- Sports: runners cover km, km and km in training. Who ran farthest?
- Surveys: of one class and of another walk to school. Which class walks more?
- Measuring: drill bits and wrenches are labeled , and inch, and you must find them in size order.
Real World Applications
Recipes
Recipes often give ingredients as fractions of a cup, and you may want to know which ingredient you need the most or the least of.
Example:
A cake uses cup of flour, cup of sugar and cup of milk. With benchmarks: , so flour is the largest amount.
A granola recipe uses cup of flour, cup of sugar, cup of milk and cup of oats.
Put the amounts in order from least to greatest.
Step 1: Choose the right answer
Rewrite all four amounts in twelfths and pick the right order:
Race Distances
Coaches compare training distances that are often given as fractions of a kilometer or a mile.
Example:
Three runners covered km, km and km. The numerators are the same, so .
In training, runner A ran km, runner B ran km, runner C ran km and runner D ran km.
Which distance is the second shortest?
Step 1: Write the mathematical expression
Rewrite every distance in twentieths and give the second shortest one as a fraction:
Survey Results
Survey results from groups of different sizes are often reported as fractions, and ranking them shows which group answered yes most often.
Example:
In a survey, of the students chose music, chose sports and chose art. Same numerators: .
Four classes were asked whether they walk to school. Yes answers: class A , class B , class C , class D .
Which class has the largest share of students who walk?
Step 1: Write the mathematical expression
Write each fraction as a decimal and give the largest one as a fraction:
Key Takeaways
- 1Ascending order goes from least to greatest (), descending order from greatest to least ()
- 2Same denominator: order the numerators
- 3Same numerator: the larger the denominator, the smaller the fraction
- 4Different denominators: rewrite every fraction with the least common denominator, order the numerators, then write the original fractions
- 5Decimals are fastest when the LCD is large and the denominators divide easily (2, 4, 5, 8, 10, 20, 25)
- 6Benchmarks , and split the list into groups, so you only compare fractions inside each group
Frequently Asked Questions
Glossary
- Ascending order
- Arranged from least to greatest, written with
- Descending order
- Arranged from greatest to least, written with
- Common denominator
- A denominator shared by several fractions after they are rewritten as equivalent fractions
- Least common denominator (LCD)
- The smallest common denominator, equal to the least common multiple of the denominators
- Benchmark fraction
- A familiar reference value such as , or used to sort fractions quickly
- Equivalent fractions
- Fractions that name the same amount, like and
Formula Card
Same denominator
Order the numerators
Same numerator
The larger denominator gives the smaller fraction
Rewriting with a common denominator
Multiply numerator and denominator by the same number k until every fraction has the LCD
Fraction to decimal
Divide the numerator by the denominator, then order the decimals