Ask Dr. Math

Elementary Archive

Browse Elementary Fractions & Decimals
Stars indicate particularly interesting answers or good places to begin browsing.

Selected answers to common questions:
    Adding and subtracting fractions.
    Finding a least common denominator (LCD).
    Dividing fractions.
    Comparing/ordering fractions; equivalent fractions.
    Reducing/simplifying fractions.
    Improper fractions and mixed numbers.
    Dividing decimals.
    Converting fractions to/from decimals.
    Rounding fractions and decimals.
    Fractions and repeating decimals.

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33 1/3 Percent as a Fraction [08/03/2003]

I need help turning percents like 33 1/3%, 2.5%, and other percents like that into fractions.

(9/2)/(3/4): A Picture [03/27/2003]

We were trying to find a division fraction question and everything we came up with turned into a multiplication fraction problem. Why is that?

Adding and Subtracting Fractions [10/25/1999]

Can you help me learn to add and subtract fractions?

Adding and Subtracting Fractions [03/05/2002]

Why don't we add or subtract the denominators?

Adding Decimals [05/26/1998]

I can't figure this out: 894.56 + 4563.5 = ?

Adding Fractions [08/13/1997]

Sally ate 1/8 of a cake and her sister ate 3/8 of it. What fraction did they eat altogether?

Adding Fractions [01/06/2003]

My problem is 3/4 + 1/6. The common denominator is 12 but it says to build up my numerator to 9/12 + 2/12 = 11/12. I don't understand how they get 9 and 2 for numerators.

Adding Mixed Numbers [04/13/1999]

How do you add mixed numbers without renaming?

Adding, Subtracting, Multiplying, Dividing Fractions [6/7/1996]

I am ten years old and I don't understand lower-term fractions.

Cancelling Fractions [03/06/2002]

How do I cancel this problem: 1/5 x 40/1 x 1/2 ?

Changing Decimals to Fractions and Reducing [12/12/2002]

Could you please help me to understand, in the simplest way, how to write a decimal as a lowest-term fraction or mixed number?

Comparing Fractions [08/04/1999]

How do you place fractions in descending or ascending order?

Comparing Fraction Size: Two Methods [10/24/2001]

What fraction is greatest, 5/13, 2/5, or 7/15?

Congruent Fractions [04/03/1997]

What are congruent fractions?

Converting a Long Decimal to a Fraction [04/11/2002]

If I have 74/13 and I want to reduce it to a mixed number, when I divide 74 by 13 I get a long mixed decimal, 5.6923076. How do I get from 5.6923076 to 5 9/13?

Converting Fractions to Decimals [01/08/1997]

How do you convert fractions to decimals? How do you turn decimals into ratios?

Converting Fractions to/from Mixed Numbers [07/21/1997]

How do you change a fraction to a mixed number in simplest form (for example 9/5)? or a mixed number to an improper fraction (like 3 1/16)?

Converting Mixed Numbers to/from Improper Fractions [10/28/2001]

How can I change mixed numbers like 1 3/4 into improper fractions, and improper fractions like 7/5 into mixed numbers?

Cross-Multiplication [08/04/2002]

Can you explain cross-multiplication?

Demonstrating Equivalent Fractions [10/25/2000]

How can my 5th grade daughter demonstrate equivalent fractions to her gifted class?

Diagram Showing Division of Fractions [01/13/2002]

I understand how to divide fractions, but would like to be able to draw this problem in a diagram: (2/3)/(3/4) = 8/9.

Divide by a Fraction [03/19/1997]

How do you divide a whole number by a fraction?

Dividing a Fraction by a Fraction [08/11/1997]

Can you help students visualize a problem such as: 1/3 / 1/2 = 2/3 ?

Dividing a Whole Number by a Fraction [04/02/1997]

How do you divide a whole number by a fraction?

Dividing by a Fraction [06/29/1999]

Why is it that when you divide by a fraction, your answer is larger?

Dividing Decimals by Whole Numbers [10/19/2002]

Dividing decimals has been hard for me to learn.

Dividing Fractions [09/08/99]

How do you divide fractions?

Dividing Fractions to find Decimals [03/12/2001]

Why does dividing the numerator by the denominator give you the decimal form of a fraction?

Division [11/25/1997]

How do you divide 1,000,000,000,000 by 999,999,999,999,999,999,999?

Draw Three Parts and Shade Two [04/12/2001]

When I draw three parts and shade two of them, what is the name of the fraction I've shaded?

Explaining Division of Fractions [08/11/1999]

Can you give a practical explanation of why the 'invert-and-multiply' rule for division of fractions works?

Finding Decimals on a Number Line [01/16/2002]

How can I find a number like 0.725 on a number line?

A Fraction and a Prime Number Question [2/9/1995]

An elementary student asks questions about fractions and prime numbers.

Fraction Bar Name [12/14/1996]

What is the name of the little line that separates the divisor from the dividend in a standard division question?

Fraction Basics [7/21/1996]

I don't understand how to do fractions.

Fraction Diagrams [03/13/2002]

In an adult condominium complex, 2/3 of the men are married to 3/5 of the women. What fraction of the residents are married?

Fraction Multiplication and Division [02/10/2001]

How do you do calculations like 2 1/10 * 7 5/8 or 27/30 over 75/100?

Fractions, Improper Fractions, Mixed Numbers [02/01/1997]

How do you turn an improper fraction into a mixed number?

Fractions in Simplest Form [01/15/1998]

How would you write 99/6 in simplest form?

Fractions in the SI System? [11/07/2001]

When using metric can 4 cm and 5 mm be written as 4 1/2 mm?

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