Author 
Message 
TAGS:

Hide Tags

Intern
Joined: 11 Oct 2009
Posts: 11

Rules for Odd and even number operations
[#permalink]
Show Tags
14 Dec 2009, 13:35
Hi all,
I was just reviewing the rules for odd and even number operations:
Odd + Odd = Even Even + Even = Even Odd +Even = Odd
Odd x Odd = Odd Even x Even = even Odd x even = even
(Essentially the only things that result in odd numbers are: odd + even = Odd and Odd x Odd = Odd)
And was wondering if anyone could confirm  do these rules also apply to subtraction and division?
Ie) odd  even = odd or even  odd = odd and Odd divided by odd = odd
Off the top of my head, they seem to work for division and subtraction as well.



Intern
Joined: 11 Dec 2009
Posts: 37
Schools: McCombs

Re: Rules for Odd and even number operations
[#permalink]
Show Tags
15 Dec 2009, 23:34
Yes, it works for subtraction, but not division. Division can result in noninteger answers so beware of division!
_________________
GMAT Retake  Summer/Fall 2010 Minimum 650, Goal 700 Resources  Kaplan Premiere, MGMAT Guides 18, OG12, Quant & Verbal
Please help me towards my goal of GMATclub tests and press +1 (kudos) if you like my posts.



Intern
Joined: 05 Nov 2014
Posts: 41
Concentration: Marketing, International Business

Rules for Odd and even number operations
[#permalink]
Show Tags
17 Jun 2015, 00:42
Is there any rule for division?
_________________
Kudos = Thanks
"Yeah, you can get a nickel for boosting Starfall, but jacking Heal's a tenday stint in county. Now lifting Faerie Fire, they just let you go for that — it's not even worth the paperwork. But Reincarnation, man! That'll get you life!"



Current Student
Joined: 20 Mar 2014
Posts: 2638
Concentration: Finance, Strategy
GPA: 3.7
WE: Engineering (Aerospace and Defense)

Re: Rules for Odd and even number operations
[#permalink]
Show Tags
17 Jun 2015, 02:04
Subanta wrote: Is there any rule for division? As mentioned in the post above yours, division is tricky. For example, 9/3 = integer but 5/3= 1.67, not an integer. 2/4= not an integer but 6/2 or 4/2= an integer. Thus, odd/odd may or may be not an integer. Similarly, even/even may or may not be an integer. The best way out is to test a couple of simple cases as shown above to tackle DS problems that deal with such equations.



Intern
Joined: 05 Nov 2014
Posts: 41
Concentration: Marketing, International Business

Re: Rules for Odd and even number operations
[#permalink]
Show Tags
15 Jul 2015, 11:16
Engr2012 wrote: Subanta wrote: Is there any rule for division? As mentioned in the post above yours, division is tricky. For example, 9/3 = integer but 5/3= 1.67, not an integer. 2/4= not an integer but 6/2 or 4/2= an integer. Thus, odd/odd may or may be not an integer. Similarly, even/even may or may not be an integer. The best way out is to test a couple of simple cases as shown above to tackle DS problems that deal with such equations. Thank You Engr2012
_________________
Kudos = Thanks
"Yeah, you can get a nickel for boosting Starfall, but jacking Heal's a tenday stint in county. Now lifting Faerie Fire, they just let you go for that — it's not even worth the paperwork. But Reincarnation, man! That'll get you life!"



Intern
Joined: 06 Aug 2014
Posts: 18

Rules for Odd and even number operations
[#permalink]
Show Tags
15 Jul 2015, 11:38
ael719 wrote: Yes, it works for subtraction, but not division.
Division can result in noninteger answers so beware of division! since even number can be written as even * odd or even * even so even / even can be even * even / even which is even even * odd / even can be odd. So even / even can be both odd and even. Similarly even / odd can be even .



EMPOWERgmat Instructor
Status: GMAT Assassin/CoFounder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 12450
Location: United States (CA)

Re: Rules for Odd and even number operations
[#permalink]
Show Tags
15 Jul 2015, 20:44
Hi abhinav008, You have to be careful about your Number Property rules; from what you've posted, you don't appear to account for NONINTEGER possibilities. For example...Even/Even COULD be even OR odd OR noninteger... eg. 8/2 = 4 8/8 = 1 8/6 = Noninteger Number Property knowledge can be quite useful on Test Day, but if you're going to take a 'theory'based approach, then you have to make sure that you haven't missed any of the possibilities. GMAT assassins aren't born, they're made, Rich
_________________
760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com
Rich Cohen
CoFounder & GMAT Assassin
Special Offer: Save $75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee www.empowergmat.com/
***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************



Intern
Joined: 13 Jul 2015
Posts: 8

Re: Rules for Odd and even number operations
[#permalink]
Show Tags
19 Jul 2015, 00:06
Hi,
another 2 (obvious) rules that derive from your own, but still need to be written (for the quick answer):
1. powers don't change the OddEven. what works for me is just "covering" the powers and continue as usual.
2. when i see then term "ax" (while a is a random integer), if a=> even, then i cover the "x" (ax is even) if a=> odd, then i cover the "a" (the even odd property of "ax" is determent solely by "x")
one more point to notice while dividing is that its a derivative of multiplication.
assuming the the multiplication is integer, the only rule is :
ODD X odd = odd(r) => odd(R)/odd = ODD or odd(r)/ODD = odd
because multiply even by any number result an even, the division of even by any number is not clear for its oddeven property.



NonHuman User
Joined: 09 Sep 2013
Posts: 8179

Re: Rules for Odd and even number operations
[#permalink]
Show Tags
03 Sep 2018, 16:02
Hello from the GMAT Club BumpBot! Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up  doing my job. I think you may find it valuable (esp those replies with Kudos). Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
GMAT Books  GMAT Club Tests  Best Prices on GMAT Courses  GMAT Mobile App  Math Resources  Verbal Resources




Re: Rules for Odd and even number operations &nbs
[#permalink]
03 Sep 2018, 16:02






