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Dr. Math FAQ:
3D and higher
Browse Elementary Fractions &
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Selected answers to common questions:
Adding and subtracting fractions.
Finding a least common denominator (LCD).
Comparing/ordering fractions; equivalent fractions.
Improper fractions and mixed numbers.
Converting fractions to/from decimals.
Rounding fractions and decimals.
Fractions and repeating decimals.
- Does My Fraction 1/1 Story Work? [11/04/2002]
Units in ratios: pitfalls of analogies and stories for understanding
- Do Fractions Have to be Equal? [05/09/2003]
A textbook defines fractions as 'one or more of the equal parts of a
whole.' Is this true? Do the parts of the whole have to be equal?
- Do We Need a Zero before the Decimal? [01/26/2005]
Do I need to use a zero to hold the dollar place if the amount is less
than a dollar? I see money amounts written both ways, as $.45 or
$0.45. Are both correct? If one is better, why is it better?
- Duelling Percentages [06/11/2002]
Why doesn't a decrease of 15%, followed by an increase of 15%, get you
back to where you started?
- Egyptian Fraction [3/29/1996]
Why did the Egyptians use a special symbol for the fraction 2/3?
- Eliminating Fractions in Division [11/20/2003]
How can I change a division involving a fraction to one involving only
- Equivalent Fractions [12/19/1996]
What are equivalent fractions and how do you use them?
- Equivalent Fractions [05/07/1999]
I am trying to understand equivalent fractions like 6/12 = 1/2.
- Equivalent Fractions [6/11/1996]
I don't understand equivalent fractions -- I understand how to do it, but
I don't understand how you would know if it is right.
- Estimating Fractions [12/02/2001]
There is a plate of assorted cookies, 1/6 chocolate chip and 1/5 peanut
butter. The rest of the cookies are regular. What fraction do the regular
- Estimating Fractions/Mixed Numbers [01/10/2002]
I don't understand how to find an estimated sum of 1/6 + 5/8 or 13 1/8
divided by 6 1/5.
- Even and Odd Fractions? [01/12/1999]
What rules would we have to have to be able to define a fraction as even
- Examples of Fraction Multiplication and Division [05/14/1998]
I get confused on how to multiply and divide fractions ...
- Explaining Rounding Using a Number Line [7/29/1996]
What is the best way to introduce and explain the term "rounding" to a
student who speaks limited English?
- Expressing a Fraction as a Decimal [8/19/1996]
How do you write 3/8 as a decimal?
- Expressing Percentages [01/26/2004]
Why do we sometimes use phrases like "4 out of 5 dentists"? Wouldn't it be more meaningful just to say 80% instead?
- Factoring and Cancelling in Long Division [08/29/2003]
How do I perform long division? i.e. 1,002,240,000 / 86400
- Figuring Out Fractions [04/28/2004]
I need help with adding and subtracting fractions, especially mixed
numbers and equivalent fractions.
- Finding a Common Denominator [02/21/2002]
Find a common denominator for each pair of fractions: 3/4,5/8; 3/4,7/ 10;
5/6,3/5; them write equivalent fractions.
- Finding a Fraction that Equals an Unending Number [07/08/2003]
Is there a way to find if there is a fraction that equals 0.777777...?
- Finding Common Denominators [06/25/2001]
What is the best way to find a common denominator?
- Finding Fractions between Fractions [01/08/2002]
What are four fractions between 1/3 and 1/2?
- Finding Fractions on a Ruler [08/16/1999]
How can I find measurements like 7/8" or 5/16" on a ruler?
- Finding Numbers Between Decimals [08/13/1998]
Find 3 decimals greater than 3.71 but less than 3.72.
- Finding the Digit of a Decimal Expansion [11/14/1998]
What digit will appear in the 534th place after the decimal point in the
decimal representation of 5/13?
- Finding What Cancels [03/26/2003]
(1 1/2)(1 1/3)(1 1/4)(1 1/5)... Find how many factors it will take to
reach the product of 1000.
- Flipping and Switching Fractions [01/18/2002]
I need to solve the following: n/2=5/10; 1/n=5/10; 1/2=n/10; 1/2=5/n.
- Fraction Division Diagrams [04/21/1999]
Diagram 1 divided by 1 1/2.
- Fraction Operations Explained [11/23/2003]
Addition, subtraction, multiplication and division of fractions are
explained through examples and helpful comments.
- Fraction or Decimal? [06/23/1998]
Which is more precise, a fraction or a decimal - for instance, 1/3 or
- Fractions and Adding Zeros [08/26/2001]
I am having problems with doing fractions on the calculator.
- Fractions and Cross Multiplication [07/14/1998]
When do you cross-multiply in solving fractions?
- Fractions and Decimals [02/15/1999]
How do you make 17/11 a proper fraction?
- Fractions and School Enrollments [02/26/2003]
The sum of 1/2, 1/3, and 1/4 of the enrollment of the Business School
is exactly the enrollment of the Language School. The sum of 1/5, 1/6,
1/7, and 1/8 of the enrollment of the Business School is exactly that
of the Design School. What are the enrollments of these three schools,
assuming no school has more than 1000 pupils?
- Fractions for 3rd and 4th Graders [2/13/1996]
I need to come up with creative and effective ways to teach fractions to
some 3rd and 4th graders.
- Fractions for Repeating Decimals [5/14/1996]
Convert 3.04050505.... into a fraction.
- Fractions in Simplest Form - When? [11/29/2001]
Should fractions always be reduced to their simplest form? Why or why
- Fractions of a Cup [04/15/2003]
A diagram: for a mixture of 3 cups concentrate and 4 cups water, how
much water and concentrate would you need to make 1 cup of mix?
- Fractions or Decimals? [05/18/1999]
Why do we use both decimals and fractions to represent amounts less than
- Fractions Table [06/20/1998]
Could you help me locate a math table for fractions to the 16th's?