GMAT Changed on April 16th - Read about the latest changes here

It is currently 27 May 2018, 08:34

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Math: Number Theory

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Intern
Intern
avatar
Joined: 01 Sep 2016
Posts: 32
Re: Math: Number Theory [#permalink]

Show Tags

New post 27 Oct 2016, 02:30
• Any positive divisor of n is a product of prime divisors of n raised to some power.



pls someone explain with example
Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 45459
Re: Math: Number Theory [#permalink]

Show Tags

New post 27 Oct 2016, 03:59
sanaexam wrote:
• Any positive divisor of n is a product of prime divisors of n raised to some power.



pls someone explain with example


For example, say n = 72. Consider it's factor 36 --> \(36 = 2^2*3^2\) --> 36 = product of prime divisors of n raised to some power.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Intern
Intern
User avatar
B
Joined: 22 May 2017
Posts: 6
Location: India
WE: Engineering (Computer Software)
CAT Tests
Re: Math: Number Theory [#permalink]

Show Tags

New post 23 May 2017, 16:47
Bunuel wrote:
NUMBER THEORY

Fractions (also known as rational numbers) can be written as terminating (ending) or repeating decimals (such as 0.5, 0.76, or 0.333333....).

--------------------------------------------------------


0.333333... looks like a recurring decimal and is not a rational number. This can be better modified as 0.33333 etc so it is less confusing in my opinion.
Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 45459
Re: Math: Number Theory [#permalink]

Show Tags

New post 24 May 2017, 04:02
workout wrote:
Bunuel wrote:
NUMBER THEORY

Fractions (also known as rational numbers) can be written as terminating (ending) or repeating decimals (such as 0.5, 0.76, or 0.333333....).

--------------------------------------------------------


0.333333... looks like a recurring decimal and is not a rational number. This can be better modified as 0.33333 etc so it is less confusing in my opinion.


0.333333... IS a rational number because it equals to the ratio of two integers: 1/3 = 0.3333......
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

1 KUDOS received
Senior Manager
Senior Manager
avatar
D
Joined: 06 Jan 2015
Posts: 375
Location: India
Concentration: Operations, Finance
GPA: 3.35
WE: Information Technology (Computer Software)
Re: Math: Number Theory [#permalink]

Show Tags

New post 28 Feb 2018, 18:18
1
This post received
KUDOS
Adding Few Formulas

Sum of First "n" natural nos = n(n+1)/2
Sum of First "n" ODD natural nos = n^2
Sum of First "n" EVEN natural nos = n (n+1)
_________________

आत्मनॊ मोक्षार्थम् जगद्धिताय च

Resource: GMATPrep RCs With Solution

Intern
Intern
avatar
B
Joined: 20 Dec 2014
Posts: 37
GMAT ToolKit User CAT Tests
Re: Math: Number Theory [#permalink]

Show Tags

New post 27 Mar 2018, 05:40
Hi Bunuel
The topic doesn’t touch up on LCM and HCF for fractions..

LCM( (a/b) , (c/d) ) = LCM(a,c)/HCF(b,d))

HCF( (a/b) , (c/d) ) = HCF(a,c)/LCM(b,d)

Please add if tested on GMAT.

Question from where I started to look for the theory:
https://gmatclub.com/forum/what-is-the- ... ml#p818818
_________________

Kindly press "+1 Kudos" to appreciate :)

Study Buddy Forum Moderator
User avatar
P
Joined: 04 Sep 2016
Posts: 973
Location: India
WE: Engineering (Other)
Premium Member CAT Tests
Math: Number Theory [#permalink]

Show Tags

New post 04 May 2018, 04:45
Bunuel niks18 gmatbusters pushpitkc VeritasPrepKarishma

I have a small query regarding rounding:

How do I interpret nearest ten, nearest hundred etc in

1234.1234

on both LHS and RHS of decimal?
_________________

It's the journey that brings us happiness not the destination.

1 KUDOS received
DS Forum Moderator
User avatar
P
Joined: 27 Oct 2017
Posts: 479
Location: India
Concentration: International Business, General Management
GPA: 3.64
WE: Business Development (Energy and Utilities)
Premium Member CAT Tests
Re: Math: Number Theory [#permalink]

Show Tags

New post 04 May 2018, 06:03
1
This post received
KUDOS
Hii

You have asked regarding rounding to nearest tens, hundred for 1234.1234 on both LHS and RHS of decimal.

First of all , Lets know what does the place signify:
we denote the digits as units, tens, hundreds, thousands before decimal and tenth, hundredth after decimal. see the sketch
Attachment:
gmatbusters3.jpg
gmatbusters3.jpg [ 27.32 KiB | Viewed 174 times ]


Rounding
Simplifying a number to a certain place value. Drop the extra decimal places, and if the first dropped digit is 5 or greater, round up the last digit that you keep. If the first dropped digit is 4 or smaller, round down (keep the same) the last digit that you keep.

It means if we round 47 to nearest ten = 50
whereas, 44 to nearest ten = 40

Now lets come to your question:
1234.1234
Rounding to nearest ten = 1230
Rounding to nearest hundred = 1200
Rounding to nearest tenth =1234.1
Rounding to nearest hundredth= 1234.12

I hope it is clear now. Fell free to tag again.


adkikani wrote:

I have a small query regarding rounding:

How do I interpret nearest ten, nearest hundred etc in

1234.1234

on both LHS and RHS of decimal?

_________________

SC: Confusable words
All you need for Quant, GMAT PS Question Directory,GMAT DS Question Directory
Error log/Key Concepts
Combination Concept: Division into groups

Study Buddy Forum Moderator
User avatar
P
Joined: 04 Sep 2016
Posts: 973
Location: India
WE: Engineering (Other)
Premium Member CAT Tests
Math: Number Theory [#permalink]

Show Tags

New post 04 May 2018, 06:56
gmatbusters

Thanks for the pic ;) , that made me wonder if the difference in position of tens on LHS and RHS
is because of raising base of 10 to exponents say 0,1 and -1. Is this how we arrive at
PLACE VALUES for a number?

Sorry, coming from engineering bakground, am still
not able to erase why aspects of logic :lol:

_________________

It's the journey that brings us happiness not the destination.

1 KUDOS received
DS Forum Moderator
User avatar
P
Joined: 27 Oct 2017
Posts: 479
Location: India
Concentration: International Business, General Management
GPA: 3.64
WE: Business Development (Energy and Utilities)
Premium Member CAT Tests
Re: Math: Number Theory [#permalink]

Show Tags

New post 04 May 2018, 07:03
1
This post received
KUDOS
yes you got it right
Attachment:
GB.jpg
GB.jpg [ 50.21 KiB | Viewed 157 times ]


adkikani wrote:
gmatbusters

Thanks for the pic ;) , that made me wonder if the difference in position of tens on LHS and RHS
is because of raising base of 10 to exponents say 0,1 and -1. Is this how we arrive at
PLACE VALUES for a number?

Sorry, coming from engineering bakground, am still
not able to erase why aspects of logic :lol:

_________________

SC: Confusable words
All you need for Quant, GMAT PS Question Directory,GMAT DS Question Directory
Error log/Key Concepts
Combination Concept: Division into groups

Re: Math: Number Theory   [#permalink] 04 May 2018, 07:03

Go to page   Previous    1   2   3   4   [ 70 posts ] 

Display posts from previous: Sort by

Math: Number Theory

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.