Plug in number strategy help....

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shayam: Junior | Next Rank: 30 Posts; Posts: 21; Joined: Wed Mar 16, 2011 12:31 pmFollowed by: 1 member; Thanked: 3 times

by shayam » Sat Oct 08, 2011 2:33 pm

Hey All,

I am just getting started.
Now,I understand that plugging in numbers is a key strategy for many type of problems and this technique comes out from exp or practice, but I am trying to create a flash list of key methods..
Request your help by adding methods not listed here...or correct me if I am wrong..

* Plug in smart numbers
for percents .. plugging in 100
for work problems - plugging in 1
for fractions .. plugging in LCM of all denominators.
for speed problems plugging numbers like 100,1000

* For word problems in general choosing smaller numbers to start offf. say.. 0,1,2,3,4 so that multiplication,exponent/division gets easier.
* Plugging in answer choices(numbers) into the problem.
* Some articles stated that I should not plug in 0,1. in certain problems. Do you guys see any problem in pluggin 0,1
* If multiple numbers are to be plugged in.. choosing prime numbers for each..
* In case of VICS.. if the question stem has defined numbers to variable .. then we should not plug in numbers..

Thanks in advance...

cHEErs

Source: Beat The GMAT — GMAT Strategy | Sat Oct 08, 2011 2:33 pm

tpr-becky: GMAT Instructor; Posts: 509; Joined: Wed Apr 21, 2010 1:08 pmFollowed by: 85 members; Location: Irvine, CA; Thanked: 199 times; GMAT Score:750

by tpr-becky » Mon Oct 10, 2011 6:24 am

I would actually suggest somewhat different criteria:

For percents use 100

for work problems use a multiple of the common factors (you don't want to deal in fractions if you don't have to)

for fraction problems - use a multiple of the Greatest common factor (again, it is easier to work with whole numbers instead of fractions)

If the word problem is short or has few actions - use small prime numbers - if it is longer choose a number between 10 and 100.

Do not use 0, 1 or numbers from the answer choices - this often creates multiple correct answers and you either get it wrong or you have to re-do the problem.

Plugging in the answers is a similar but completely different technique to be used in different circulstances (i.e. when the algebra gets too hard for you personally to manipulate confidently you should use the answers) However, if there are variables in the answers you should always plug in a number.

Becky
Master GMAT Instructor
The Princeton Review
Irvine, CA

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