GRE Math : How to find the lowest / least common denominator

Study concepts, example questions & explanations for GRE Math

Create An Account

All GRE Math Resources

13 Diagnostic Tests 452 Practice Tests Question of the Day Flashcards Learn by Concept

Example Questions

Example Question #1054 : Gre Quantitative Reasoning

What is the least common denominator of 150 and 175 ?

Possible Answers:

26250

1050

Correct answer:

1050

Explanation:

To find the least common denominator of two numbers, it is easiest first to factor them into prime factors:

$150=25\cdot6=5^2\cdot2\cdot3=2\cdot3\cdot5^2$

$175=5^2\cdot7$

Now, you need to compare each number and choose the case in which the prime factor has the highest power. Therefore, since and are found only in 150 , you will select those. You can take "either" 5^2 . Finally, the in 175 is the largest factor of . Your LCD is found by multiplying all of these together:

$2\cdot3\cdot5^2\cdot7 = 1050$

Report an Error

Example Question #1 : How To Find The Lowest / Least Common Denominator

Simplify:

$\frac{4}{35}+\frac{7}{30}$

Possible Answers:

$\frac{73}{210}$

$\frac{81}{11}$

$\frac{91}{5}$

$\frac{814}{105}$

$\frac{9141}{1050}$

Correct answer:

$\frac{73}{210}$

Explanation:

To begin to solve this, you need to find the least common denominator of and . The easiest way to do this is to begin by factoring them into prime factors:

$35=5\cdot7$

$30=2\cdot3\cdot5$

The LCD is found by selecting the largest power for each factor across the two values. Therefore, you will take ,, and from and the from the . Your LCD is therefore:

$2\cdot3\cdot5\cdot7=210$ .

Now, apply this to your fractions:

$\frac{4}{35}\cdot\frac{6}{6}+\frac{7}{30}\cdot\frac{7}{7}=\frac{24}{210}+\frac{49}{210}=\frac{73}{210}$

Report an Error

Example Question #3 : How To Find The Lowest / Least Common Denominator

In simplest form, $\frac{11}{15}+\frac{17}{20}=$

Possible Answers:

$\frac{19}{12}$

$\frac{28}{35}$

$\frac{187}{300}$

$\frac{117}{1520}$

Correct answer:

$\frac{19}{12}$

Explanation:

First, find the smallest number that both and will factor into, which is .

This means that the fist fraction should be multiplied by and the second should be multiplied by .

Therefore,

$\frac{11}{15}\cdot \frac{4}{4}+\frac{17}{20}\cdot\frac{3}{3}=\frac{44}{60}+\frac{51}{60}$ .

Then, add the numerators while the denomenators stay the same:

$\frac{44}{60}+\frac{51}{60}=\frac{44+51}{60}=\frac{95}{60}$ .

Then, reduce the fraction to its lowest terms:

$\frac{95}{60}=\frac{5\cdot 19}{5 \cdot 12}=\frac{19}{12}$ .

Report an Error

All GRE Math Resources

13 Diagnostic Tests 452 Practice Tests Question of the Day Flashcards Learn by Concept

Popular Subjects

ACT Tutors in Boston, Computer Science Tutors in Washington DC, ACT Tutors in Dallas Fort Worth, Chemistry Tutors in New York City, Physics Tutors in Los Angeles, LSAT Tutors in Chicago, SAT Tutors in Philadelphia, ACT Tutors in Phoenix, MCAT Tutors in San Francisco-Bay Area, SSAT Tutors in New York City

Popular Courses & Classes

LSAT Courses & Classes in Atlanta, Spanish Courses & Classes in Philadelphia, GMAT Courses & Classes in Denver, ISEE Courses & Classes in San Francisco-Bay Area, ACT Courses & Classes in Houston, SSAT Courses & Classes in Philadelphia, LSAT Courses & Classes in Denver, GRE Courses & Classes in Los Angeles, SSAT Courses & Classes in San Francisco-Bay Area, SSAT Courses & Classes in Phoenix

Popular Test Prep

LSAT Test Prep in Dallas Fort Worth, ISEE Test Prep in Boston, GRE Test Prep in Los Angeles, ISEE Test Prep in Phoenix, ACT Test Prep in Houston, GRE Test Prep in Houston, SAT Test Prep in Phoenix, MCAT Test Prep in San Francisco-Bay Area, GMAT Test Prep in Dallas Fort Worth, MCAT Test Prep in Houston

DMCA Complaint

If you believe that content available by means of the Website (as defined in our Terms of Service) infringes one or more of your copyrights, please notify us by providing a written notice (“Infringement Notice”) containing the information described below to the designated agent listed below. If Varsity Tutors takes action in response to an Infringement Notice, it will make a good faith attempt to contact the party that made such content available by means of the most recent email address, if any, provided by such party to Varsity Tutors.

Your Infringement Notice may be forwarded to the party that made the content available or to third parties such as ChillingEffects.org.

Please be advised that you will be liable for damages (including costs and attorneys’ fees) if you materially misrepresent that a product or activity is infringing your copyrights. Thus, if you are not sure content located on or linked-to by the Website infringes your copyright, you should consider first contacting an attorney.

Please follow these steps to file a notice:

You must include the following:

A physical or electronic signature of the copyright owner or a person authorized to act on their behalf; An identification of the copyright claimed to have been infringed; A description of the nature and exact location of the content that you claim to infringe your copyright, in \ sufficient detail to permit Varsity Tutors to find and positively identify that content; for example we require a link to the specific question (not just the name of the question) that contains the content and a description of which specific portion of the question – an image, a link, the text, etc – your complaint refers to; Your name, address, telephone number and email address; and A statement by you: (a) that you believe in good faith that the use of the content that you claim to infringe your copyright is not authorized by law, or by the copyright owner or such owner’s agent; (b) that all of the information contained in your Infringement Notice is accurate, and (c) under penalty of perjury, that you are either the copyright owner or a person authorized to act on their behalf.

Send your complaint to our designated agent at:

Charles Cohn Varsity Tutors LLC
101 S. Hanley Rd, Suite 300
St. Louis, MO 63105

Or fill out the form below:

Do not fill in this field

Contact Information

* Full legal name

Company name

* Phone number

* Email address

Address

* Address1

Address2

* City

* State

* Zipcode

* Country

Complaint Details

* URL of copyrighted work (where your original material is located)

* Please describe the copyrighted work so that it may be easily identified

I am the owner, or an agent authorized to act on behalf of the owner of an exclusive right that is allegedly infringed.

I have a good faith belief that the use of the material in the manner complained of is not authorized by the copyright owner, its agent, or the law.

This notification is accurate.

I acknowledge that there may be adverse legal consequences for making false or bad faith allegations of copyright infringement by using this process.

* Signature (your digital signature is legally binding)

Email address:
Your name:
Feedback:

GRE Math : How to find the lowest / least common denominator

Study concepts, example questions & explanations for GRE Math

All GRE Math Resources

Example Questions

Example Question #1054 : Gre Quantitative Reasoning

Example Question #1 : How To Find The Lowest / Least Common Denominator

Example Question #3 : How To Find The Lowest / Least Common Denominator

All GRE Math Resources

Report an issue with this question

DMCA Complaint

Contact Information

Address

Complaint Details